I tried Grok 4.5 with Grok Build CLI — A comparison of responses with Opus 4.8, Sonnet 5, and GPT-5.5

I tried Grok 4.5 with Grok Build CLI — A comparison of responses with Opus 4.8, Sonnet 5, and GPT-5.5

xAI released Grok 4.5, which I tested using Grok Build CLI in headless mode. In this verification environment, I used it by authenticating via browser with an account subscribed to X Premium+. I used multiple prompts including drawing AWS architecture diagrams, organizing vague requirements, and observing response styles, and compared the responses with Kiro CLI (Claude Opus 4.8 / Sonnet 5) and Codex CLI (GPT-5.5).
2026.07.12

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Introduction

On July 8, 2026, xAI released Grok 4.5.

According to the official xAI announcement (x.ai/news/grok-4-5), it achieved the top ranking among listed models on SWE Marathon (29.0%) and 83.3% on Terminal Bench 2.1. API pricing is $2 input / $6 output (per million tokens), and the average output token count for SWE Bench Pro tasks is approximately 1/4.2 that of Opus 4.8 (max).

While Grok Build CLI is officially called a "coding agent," it can also be used generically to obtain responses to arbitrary prompts. For this verification, I used an account with an active X Premium+ subscription, authenticated via browser using grok login.

Verification Details

Installing Grok Build CLI and Headless Execution

The verification environment is as follows.

Item Value
OS Fedora Linux 44 (Asahi Remix)
Architecture aarch64 (Apple Silicon)
Grok Build CLI v0.2.93 (stable)
Kiro CLI v2.12.0
Codex CLI v0.144.1

Installation

You can install with a one-liner.

curl -fsSL https://x.ai/cli/install.sh | bash
$ grok --version
grok 0.2.93 (f00f96316d) [stable]

The binary is placed at ~/.grok/bin/grok.

Authentication

On first launch, a browser opens and you sign in with your X account. The authentication method is OIDC, with the issuer being https://auth.x.ai.

After authentication is complete, the token is cached in ~/.grok/auth.json. You can then run the CLI without opening a browser, and no API key configuration is required.

X Premium+ Setup

The X account used for verification has an active Premium+ subscription.

X Subscription

In Grok's data control settings, I have opted out of using data for training. I also manually set coding_data_retention_opt_out: true in ~/.grok/auth.json on the CLI side.

Grok Settings_Data Control

Grok usage resets weekly and is displayed as a percentage. The specific number of credits is not disclosed. Before and after running the three prompt comparisons, the weekly usage included in the subscription changed from 55% to 57%.

Usage

Headless Mode

Adding the -p (--single) option returns the result to standard output in a single prompt execution without opening an interactive session.

grok -p "Explain this codebase" --output-format plain --effort medium

Main options:

Option Description
-p / --single Headless mode (single prompt execution)
--prompt-file Load prompt from file
--output-format Output format (plain / json / streaming-json)
-m / --model Model specification (at time of verification: grok-4.5 500K / grok-composer-2.5-fast 200K)
--effort Inference depth (high / medium / low)

Prompt Comparison: AWS Architecture Diagram (DrawIO XML) Generation

I gave the same prompt to four agents and had them generate XML in DrawIO format. Note that the inference settings that can be specified differ between CLIs (Grok: --effort medium, Kiro: --effort xhigh). This article compares the output results using the settings specified at execution time.

Prompt

Please create an AWS architecture diagram in DrawIO XML format with the following requirements. Use AWS Simple Icons (AWS 2024 shape library).

Requirements:

  • Deliver content to users via CloudFront
  • VPC in multi-AZ configuration (2 AZs)
  • Load balancing with ALB (Application Load Balancer)
  • One EC2 instance per AZ (2 total)
  • RDS in multi-AZ deployment (primary + standby)
  • Place each component in appropriate subnets (Public/Private)

Return only the complete XML that can be loaded in DrawIO. No explanatory text needed.

Results

All four agents output XML. Grok 4.5, Opus 4.8, and Sonnet 5 could be loaded directly in DrawIO, while Codex (GPT-5.5) could be loaded after fixing the diagram name.

Below are the results of opening each output in DrawIO.

Grok 4.5

AWS Architecture Diagram_Grok4.5

This was the most detailed output. It includes CIDR notation, three-tier separation of Public/Private/DB subnets, protocol labels (HTTPS/HTTP/SQL), and Synchronous Replication arrows.

Kiro — Opus 4.8

AWS Architecture Diagram_Opus48

A compact output. Only Public/Private two tiers, with EC2 and RDS sharing the same Private Subnet. The ALB is placed at the top of the VPC in a cross-AZ configuration.

Kiro — Sonnet 5

AWS Architecture Diagram_Sonnet5

Route 53 has been added (outside requirements). Internet Gateway is explicitly shown, with a three-tier configuration of Public/Private(App)/Private(DB). It depicts one ALB per AZ, but since ALB is actually a single resource spanning AZs, this is somewhat inaccurate as an architecture representation.

Codex — GPT-5.5

AWS Architecture Diagram_Codex(GPT-5.5)

Label overlapping is noticeable ("PuHTTP/HTTPSA", "AmaDB, EC2 Web/App", etc., with coordinate misalignment). The structure is understandable but the appearance is broken.

Prompt Comparison: Specification Organization for Ambiguous Requirements

Prompt

A user told you "I want to complete in-house attendance management entirely in Slack." As a requirements definition, please list 5 each of the necessary features, technology selections, and anticipated challenges.

Comparison

Perspective Grok 4.5 Opus 4.8 Sonnet 5 GPT-5.5
Adherence to "5 items" ✅ (5 items each + supplements) ✅ (5 items each) ✅ (5 items each) ✅ (5 items each)
Feature granularity Table format with summaries. Covers from time-stamping to export Bullet points. Includes reminders and compliance notifications Bullet points. Separates clock-in, clock-out, and breaks as distinct features Bullet points. Concise 5 items
Technology selection rationale Reasons stated for each technology (table format) Reasons stated for each technology (prose) Reasons stated for each technology (prose) One-line reason for each technology
Specificity of challenges Digs into legal compliance, Article 36 agreements, and location data Mentions legal compliance, backup during failures, and integration References legal evidentiary value, offline countermeasures, and vendor lock-in Concisely lists proxy time-stamping, time zones, and vendor risks
Volume Most (includes tables + supplements) Medium Medium Least (concise)
Full response text from each agent (click to expand)

Grok 4.5's Response

Based on the premise of "running the cycle from time-stamping → application → approval → aggregation on Slack," here is an organized draft for requirements definition.

1. List of Necessary Features (5)

# Feature Overview
1 Time stamping (clock-in, clock-out, breaks) Record stamps using Slack buttons/shortcuts/slash commands. Automatic recording of stamp times, detection of tardiness/early departure, work style tags like remote/in-office.
2 Application workflow for leave, overtime, etc. Enter applications for paid leave, half-day, compensatory leave, overtime, substitute work, etc. via modal → approval request to supervisor → approval/rejection notification. Overview of application status.
3 Approval and reminders DM/channel notifications to supervisors, reminders for unapproved items, proxy approval, escalation. Notification of approval results to the applicant and HR.
4 Viewing and correcting attendance data Monthly attendance confirmation by the individual, application for correction of missed stamps, modification/finalization by administrators. Daily/monthly summaries (work hours, overtime, remaining paid leave, etc.).
5 Aggregation, export, and external integration Monthly close, CSV/API output for payroll calculations, integration with existing HR/payroll/accounting systems. Operation logs for auditing.

Additional items that are often needed: holiday calendars, core time/flextime support, Article 36 alerts, location information and IP restrictions (countermeasures against fraudulent time-stamping), multilingual/multi-location support.

2. Technology Selection (5)

# Domain Recommended Candidates Selection Rationale
1 Slack integration Slack Bolt (Node.js/Python) + Socket Mode or HTTP Request URL Easy to implement modals, interactive, and events with the official SDK. Socket Mode is advantageous when there are internal firewall restrictions.
2 Backend Node.js (TypeScript) or Python (FastAPI) Choose based on compatibility with Bolt, asynchronous processing, and internal skill sets.
3 Data store PostgreSQL (main) + Redis (cache/queue) Transactions and history are critical for attendance. Jobs (close processing, reminders) should be queued.
4 Authentication/authorization Slack OAuth/OpenID Connect + internal IdP (Okta, Azure AD, etc.) integration Link Slack users with employee master data. RBAC based on department and job title.
5 Infrastructure/operations Containers (ECS/Cloud Run/k8s) + managed DB + monitoring (CloudWatch/Datadog, etc.) Ensure availability, audit logs, and backups. Nightly batches and monthly closes run on a scheduler.

3. Anticipated Challenges (5)

# Challenge Content and Direction for Countermeasures
1 Legal/labor compliance Compliance with the Labor Standards Act (objective recording of stamps, overtime limits, paid leave management). Explicitly define rounding rules and handling of late-night/holiday work in specifications, and review with the HR team.
2 Fraudulent time-stamping/impersonation Stamping on behalf of others, spoofing via VPN, etc. Deter with IP restrictions, optional device/location checks, tamper-prevention of stamp logs, and administrator audits.
3 Dependence on Slack outages/missed notifications If Slack goes down and time-stamping becomes impossible, operations halt. Consider web/mobile fallbacks, post-sync of offline stamps, and email as a backup for important notifications.
4 Complexity of organizational master data and permissions Concurrent positions, proxy approvals, organizational restructuring, secondments. Sync design with the HR master, immediate reflection of permission changes, and history management tend to become bottlenecks.
5 Duplicate management with existing systems Data inconsistencies with payroll, HR, and existing attendance systems. Decide on the source of truth for the master, and clarify sync direction and rules for post-close corrections.

Kiro (Opus 4.8)'s Response

Here is an organized requirements definition for completing in-house attendance management in Slack.

List of Necessary Features (5)

  1. Time-stamping feature (clock-in, clock-out, breaks) — Stamp via slash commands (e.g., /punch in), shortcuts, or button messages. Includes reminder notifications to prevent forgetting.
  2. Work status inquiry/correction requests — Individuals can check their work hours for the day/month and apply for corrections to stamping errors. It is preferable to include an approval flow for corrections.
  3. Approval workflow (overtime, leave, corrections) — Application/approval to supervisors and completion via interactive Slack messages (approval/rejection buttons). Approval results are automatically notified to applicants.
  4. Aggregation and report output — Automatically aggregate monthly work hours, overtime, and leave days taken, and output CSV/spreadsheets for administrators. Also consider integration with payroll systems.
  5. Alerts and compliance notifications — Automatically notify individuals and managers when long working hours (approaching Article 36 limits), missed breaks, or missed stamps are detected.

Technology Selection (5)

  1. Slack app platform: Bolt (official Slack SDK) — Bolt for Python or JavaScript. Uniformly handles slash commands, shortcuts, Block Kit, and event subscriptions, with strong official support.
  2. UI construction: Block Kit + Modals — Build intuitive stamping/application UIs with buttons and input forms (modals). Minimizes screen transitions outside Slack.
  3. Execution environment: Serverless (AWS Lambda + API Gateway) — Stamping is event-driven and intermittent, making it well-suited for serverless. Balances cost efficiency and scalability.
  4. Data store: RDB (Amazon RDS/DynamoDB) — A relational DB is the primary candidate because attendance requires accuracy and aggregation. Consider an append-only table design for audit log purposes.
  5. Authentication/user integration: Slack user ID × employee master — Link Slack OAuth/user IDs with the employee directory. For companies with SSO integration, verify identity against the IdP.

Anticipated Challenges (5)

  1. Legal/labor compliance — Under the Labor Standards Act, attendance records must be "objective records." Confirmation with a labor attorney and legal team is essential to determine whether Slack stamps qualify as objective records.
  2. Reliability of time-stamping/fraud prevention — Since Slack can be operated from anywhere, it is difficult to guarantee that the person is "actually at work/in the office." Adjustment with operational requirements is needed on how far to go with location information, IP restrictions, and impersonation countermeasures.
  3. Dependency on Slack outages and API rate limits — If Slack goes down, time-stamping becomes impossible. Design responses to fallback measures and rate limits/3-second response limits are required.
  4. Data integrity and correction operations — Exception handling for missed stamps, duplicate stamps, timezone discrepancies, etc. Correction history must be maintained in an auditable form.
  5. Integration with existing systems and migration — Integration specifications with payroll and HR systems, migration from existing attendance systems, and handling of parallel operation periods.

Kiro (Sonnet 5)'s Response

Here is a draft requirements definition for a system to complete attendance management in Slack.

List of Necessary Features (5)

  1. Clock-in/clock-out feature — Stamp via slash commands (/clockin, /clockout) or shortcut buttons. Stamp times also consider UTC/JST conversion.
  2. Break and temporary absence management — Record break start/end and personal outings. Supports multiple temporary absences.
  3. Attendance history/summary confirmation — A command that allows individuals to check their own monthly attendance in Slack.
  4. Application/approval workflow — Leave requests, overtime applications, stamp correction requests, etc. are submitted in Slack, and supervisors approve via button operations.
  5. Reminder and alert notifications — Automatic notifications to the individual and their supervisor when stamp reminders are missed or overtime hours exceed a threshold.

Technology Selection (5)

  1. Slack Bolt (Node.js/Python) — Official Slack SDK. Can handle Events API, Slash Commands, and Interactivity in an integrated manner.
  2. AWS Lambda + API Gateway — Processes events from Slack serverlessly. Cost-efficient given stamp frequency.
  3. DynamoDB or Aurora Serverless — DynamoDB for simple key-value access common in stamping, RDBMS for aggregation-heavy needs.
  4. EventBridge Scheduler — Scheduling for periodic reminders (missed stamp checks, monthly close processing).
  5. API integration layer with existing attendance/payroll systems — Adapter layer for integration with freee HR, SmartHR, Bugyo Cloud, etc.

Anticipated Challenges (5)

  1. Legal stamp accuracy and evidentiary value — Under the Labor Standards Act, attendance records must be objective records. Whether stamp button operations in Slack alone can prove "the individual stamped" requires careful consideration.
  2. Alternative measures during offline/outage situations — If Slack itself or the network goes down and stamping becomes impossible, operations halt. An emergency alternative application flow is needed.
  3. Data consistency with existing payroll/HR systems — Integration of data into payroll systems is ultimately essential. There is a risk of format inconsistencies and timezone discrepancies.
  4. Countermeasures against fraudulent stamping and impersonation — Issues with the reliability of stamps made via another person's PC or account, and stamps not accompanied by location information.
  5. Dependency risk on Slack workspace operations — Structural risk that business operations are directly affected by vendor-side changes such as Slack plan changes, API specification changes, and rate limits.

Codex (GPT-5.5)'s Response

Here is a draft requirements definition based on the premise of completing in-house attendance management in Slack.

List of Necessary Features

  1. Clock-in, clock-out, break, and return stamping features
  2. Application features for paid leave, absence, tardiness, early departure, etc.
  3. Approval and rejection features by supervisors
  4. Attendance status overview and monthly aggregation features
  5. Notification features for missed stamps and applications

Technology Selection

  1. Slack App / Slack Bolt — To implement commands, buttons, and modals in Slack.
  2. Backend: Node.js/TypeScript or Python — Used for Slack API integration, attendance logic, and approval flow processing.
  3. Database: PostgreSQL/MySQL — Manages stamp history, applications, approval states, and user information.
  4. Hosting: AWS/Google Cloud/Azure — Used for API servers, batch processing, log management, and monitoring.
  5. Authentication/integration: Slack OAuth/SSO/internal HR system API — To link Slack users with employee information.

Anticipated Challenges

  1. Ensuring stamp accuracy — Proxy stamping, missed stamps, timezones, and handling remote work are challenges.
  2. Compliance with labor rules — Compliance with laws and internal regulations such as overtime, paid leave, break times, and Article 36 agreements is necessary.
  3. Complexity of approval flows — Need to support departments, job titles, proxy approvals, and multi-stage approvals.
  4. Integration with existing systems — Data synchronization with payroll, HR master data, and existing attendance systems is necessary.
  5. Security and audit compliance — Management of personal information, attendance logs, change history, permission management, and audit trails is important.

Prompt Comparison: Metacognition (Response Style Observation)

Prompt

Please list 3 areas you are good at and 3 areas you are weak at, and honestly describe your position when compared to other LLMs (Claude, GPT, Grok).

Comparison

The results of this prompt are not used as factual evidence of the models' actual capabilities. They are treated as observations of differences in response style regarding "how each agent describes itself."

Perspective Grok 4.5 Opus 4.8 Sonnet 5 GPT-5.5
Self-introduction Explicitly states "xAI's Grok (Grok 4.5)" Explicitly states "agent running on claude-opus-4.8" Explicitly states "using claude-sonnet-5" Does not state model name, positions itself as "a practical LLM"
How strengths are described Emphasizes "hands-on work to completion" and "directness" Emphasizes "execution capability in code implementation and tool integration" and "caution" Emphasizes "development work rooted in the local environment" and "parallel processing" Emphasizes "codebase investigation and implementation correction" and "debugging"
How weaknesses are admitted Specific ("tends toward overconfidence," "UX requires humans") Specific ("tends to over-confirm," "not good at numerical calculations") Declines with "not in a position to evaluate objectively" Honestly admits "ambiguous and sensory written expression"
References to other models Compares by axis in table format. Writes fairly Acknowledges Grok's strengths (real-time capability) Cautious, stating "I'll avoid this as it would be speculation" Acknowledges each model's strengths while defining its own domain
Overall tone Confident and direct. Self-described as "a field engineer" Calm. Self-aware of being safety-oriented, structures strengths and weaknesses Most cautious. Avoids definitive statements Practical. Defines its own domain simply

Grok 4.5 was the most verbose when referencing other models, even creating a comparison table. It clearly positioned "directness and fewer restrictions" as its own stance. Meanwhile, Sonnet 5 stood out for its posture of avoiding superiority/inferiority comparisons with other models, stating "I'm not in a position to evaluate objectively."

Full response text from each agent (click to expand)

Grok 4.5's Response

Areas of Strength (3)

  1. Tool-driven practical tasks (implementation, investigation, editing) — The center is "hands-on work to completion" such as reading and fixing code, running commands, searching the web/X, and editing files. Easy to move quickly from design to implementation to verification.
  2. Wide context and direct explanation — Even with long conversations or large codebases, easy to extract key points, compare, and organize. Even with vague requests, I advance by forming hypotheses and state premises when necessary.
  3. Integration of the latest information from multiple sources — Using web search, X search, etc., I can gather public information and organize it including opposing views. For both technical topics and current affairs, I can answer based on "what's happening now."

Areas of Weakness (3)

  1. Complete autonomy/perfect self-verification — With large designs or long changes, oversights, misaligned premises, and insufficient testing can occur. Without human review or the instruction "please verify again," I tend toward overconfidence.
  2. Final judgments in strict specialized domains — In high-responsibility domains like medicine, law, and accounting, I can provide "reference information" but cannot replace a specialist's final judgment.
  3. The "authenticity" of sensory/physical creation — I can create text, images, and code, but I am weak at the final adjustment of physical touch, sound, atmosphere, and the subtle tone of a brand rooted in human experience.

My Position Compared to Other LLMs

Axis Claude series GPT series Grok (me)
Care in code/long text Strong (readability, caution) Strong (versatility, tool ecosystem) Strong in practical implementation and tool integration, but may fall short of Claude in textual "polish"
Directness/fewer restrictions Cautious, safety-oriented Balanced Relatively straightforward, designed with lighter censorship
Real-time/X integration Average to weak Supplemented with plugins, etc. Current information assuming X and search tends to be a strength
Deep reasoning/deliberation Very strong depending on model Reasoning-specialized like o-series is strong Can handle practical reasoning, but in extremely difficult problems and competitive math, may lose to dedicated reasoning models

Rough position: More of "an engineer working hands-on in the field" than "the best academic paper award winner in the lab."


Kiro (Opus 4.8)'s Response

I will answer honestly. First, as a premise: I (Kiro) am an agent running on a model called claude-opus-4.8.

Areas of Strength

  1. Execution capability in code implementation and tool integration — Rather than just code proposals, I can actually perform file reading/writing, search, build/test execution, AWS operations, and verify up to verification.
  2. Consistency and careful reasoning over long contexts — Claude-series models are relatively good at maintaining long instructions and complex constraints while providing coherent explanations.
  3. Caution and safety-side judgment — "Resistance to going out of control," such as confirming before destructive operations and reaching conclusions after verification, is a strength from both design and model perspectives.

Areas of Weakness

  1. Latest information/real-time capability — There are temporal limits to training data, and latest events, prices, and version specifications cannot be answered without searching.
  2. Precise numerical calculations/large-scale logical exploration — Calculator-level accuracy and searching vast combinations are fundamentally weak, with hallucinations mixed in.
  3. Verbosity and over-confirmation due to excessive caution — Due to the design of erring on the side of safety, there is a tendency to interject confirmations or have long preambles in situations where the user wants things to proceed quickly.

My Position Relative to Other LLMs

  • Versus GPT series: Comparable to superior in coding, long-text instruction adherence, and safety. GPT series may take the lead in the versatility of the general ecosystem and the responsiveness for general users.
  • Versus Grok series: Grok has the advantage in real-time information and casual, uninhibited discourse. On the other hand, I am more suited for code reliability, safe operations, and consistency over long contexts.
  • Summary: My position is "an agent that dives deep into development workflows, actually gets hands-on, and completes things reliably and safely."

Kiro (Sonnet 5)'s Response

I will limit my answer on strengths and weaknesses to what I can say from the tool group I actually have and its design, rather than speculation.

Areas of Strength

  1. Development work rooted in the local environment — File reading/writing, code search (symbol search based on AST analysis), bash command execution, and git workflows are integrated.
  2. Decomposition of complex tasks and parallel processing — There is a feature to delegate to sub-agents, enabling parallel processing of multiple independent sub-tasks.
  3. Safety-conscious execution — There are clear guardrails for destructive operations, and the design judges whether to confirm or proceed autonomously based on the level of risk.

Areas of Weakness

  1. Latest information/currency — Knowledge based on training data has limits, and accuracy cannot be guaranteed for events, prices, and recent product specifications without using web search tools.
  2. Flexibility in general creative/casual conversation — Due to a response style optimized for development and practical tasks, it tends to give a stiff impression in long-form creative writing and casual dialogue.
  3. Breadth of multimodal capabilities — While image reading is possible, a wide range of modalities such as image generation, audio, and video cannot be handled.

Comparison with Other LLMs

Honestly, I (Kiro CLI) myself am not a "model" but rather an agent/tool layer running on Claude as the base model. I am not in a position to objectively evaluate the raw performance superiority/inferiority of the base model. If I were to make definitive statements about superiority/inferiority, it would be speculation, so I will avoid that.


Codex (GPT-5.5)'s Response

To be honest about my position, I am not a "general-purpose conversational model" but rather a practical LLM oriented toward code reading, implementation, debugging, and repository work.

Areas of Strength

  1. Codebase investigation and implementation correction — I am good at reading existing code and making changes in line with the design intent.
  2. Technical decomposition and realistic design judgment — I am good at reducing requirements to implementation units and formulating safe change policies while avoiding over-engineering.
  3. Error analysis and debugging support — I am suited to work that narrows down the cause from stack traces, logs, failing tests, type errors, etc., and brings it to a correction proposal.

Areas of Weakness

  1. Optimization of ambiguous and sensory written expression — In poetic expression, advertising copy, and literary nuance adjustment, there are cases where I fall short of Claude's textual softness.
  2. Immediate follow-up to the latest external information — I am weak on real-time information. Confirmation is needed for the latest news, stock prices, and recent product specifications.
  3. Reading social/political/cultural atmosphere — For uses like Grok that lightly picks up on current events and internet culture context, I tend to be somewhat stiff and cautious.

Comparison with Other LLMs

Compared to Claude, there are cases where I fall short in the naturalness of text and the warmth of long-text comprehension, but I have strengths in actually advancing the work of code changes. Compared to Grok, while I am inferior in real-time capability and casual responses to current events, I am more reliable for calm technical judgment and code work. In summary, my position is "not the most charming model for casual conversation or creative work, but a practical model for reading and fixing code and advancing technical challenges."

Practical Example: Comparing Work Report Generation

Using Kiro CLI's prompt log as source data, I generated work reports from the same log using both Kiro (Opus 4.8) and Grok 4.5, and compared the differences in output.

The method of generating work reports from prompt logs is introduced in the following article. This section focuses on comparing outputs without explaining the method.

https://dev.classmethod.jp/articles/kiro-prompt-log-analysis/

Comparison Results

The results below are from inputting July 10th logs and extracting only blog writing-related tasks.

Perspective Kiro (Opus 4.8) Grok 4.5
Number of extracted tasks 5 7
Coverage range Focused on published articles Comprehensive, including items still in preview stage
Perspective of challenge setting Output-oriented ("what to create") Reader-oriented ("what needed to be communicated")
Specificity of impressions Next action + hypothesis ("confirm quality with medium setting") Principle description ("thorough adherence to masking policy is important")

Task granularity/comprehensiveness: Grok listed all 7 tasks including unfinalized (preview stage) ones. Kiro tended to narrow down to the 5 confirmed published items, excluding those still in the preview stage.

How challenges are written: For example, regarding the Redshift article, Kiro wrote "verify and introduce the actual behavior of track switching" from an output perspective. Meanwhile, Grok wrote "needed to convey including the actual behavior of track switching (the point that it cannot be reverted/is placed on hold)" incorporating what readers want to know.

Specificity of impressions: Kiro wrote "I will confirm in the next article whether the review quality stays at an appropriate level with the medium setting for Codex/Grok," writing the next step including a hypothesis. Grok limited itself to principle descriptions such as "ensuring file retention of verification logs and thorough adherence to masking policy is important."

Excerpts from actual outputs — Comparing task descriptions for the Redshift article (click to expand)

Kiro (Opus 4.8)'s Output

3. Redshift RG Instance Track Change Article (2.0h)

  • Challenge: In response to Amazon Redshift RG instance support for Trailing Track, verify and introduce the actual behavior of maintenance track switching.
  • Response: Implemented switching verification from Trailing to Current (completed in approximately 5 minutes, confirmed upgrade from Patch 201 → 202), confirmed pending behavior of Current → Trailing, organized operational impact of differences between patches, differentiation from preceding articles (focused on actual behavior by introducing with card links), and adjusted summary wording.
  • Result: [Completed] Article published. Title confirmed as "I tried changing the RG instance track of Amazon Redshift."

Grok 4.5's Output

3. Amazon Redshift RG Instance Trailing Track Switching Verification Article (1.5h)

  • Challenge: Needed to convey that Trailing Track is now available for RG instances, including the actual behavior of track switching (the point that it cannot be reverted/is placed on hold).
  • Response: Confirmed cluster startup and Track changes in the verification account, fact-checked official differences, organized role distribution with preceding articles, performed multiple reviews, and conducted preview confirmation.
  • Result: [Completed] Centered the article on the point that Trailing → Current is applied in the maintenance window and upgraded, while Current → Trailing is not downgraded.

Comparison of Impressions

Kiro (Opus 4.8):

Blog planning skill | Impression: I will confirm in the next article whether the review quality stays at an appropriate level with the medium setting for Codex/Grok. If excessive pointing out decreases, it is expected that the workload for adoption/rejection decisions can also be reduced.

Grok 4.5:

Blog planning skill | Impression: Since unimplemented procedure descriptions and unfounded "conventional" assertions can be mixed in via reviews, ensuring file retention of verification logs and thorough adherence to masking policy is important.

Practical Example: Utilizing for Plan Document Review

I conducted a plan document review for this very article itself using three models: Opus 4.8, Grok 4.5, and Codex (GPT-5.5). I used a review prompt that outputs issues affecting article viability from the perspectives of structure, technical verification, and scope, with the same plan.md as input.

Distribution of Issues Pointed Out

Issue Noted Opus 4.8 Grok 4.5 Codex (GPT-5.5)
Undefined observation items (Prompts 3 & 4)
Confirmation of publishability of work reports
Risk of using Prompt 4 as basis for characteristic evaluation
Explicitly stating sources for benchmarks and pricing
Insufficient coding agent verification
Insufficient organization of "free" premise
Risk of log filename overwriting
Prevention of authentication information in publications

There were 3 common issues (Opus + Grok), 1 unique to Opus, 2 unique to Grok, and 2 unique to Codex.

Excerpts from review actual outputs (click to expand)

Grok 4.5's Review Issues (excerpt)

Issue: The article's claim is "trying Grok Build CLI (coding agent)," but the verification consists almost entirely of one-shot prompt response comparisons for architecture explanations, DrawIO XML, requirements organization, and self-reporting, and does not include verification as a coding agent (repository operations, tool usage, multi-step implementation/correction, etc.).

Reason: As is, the verification results cannot support the claim/conclusion of "tried the CLI as a coding agent," resulting in a critical mismatch between the article's main purpose and the verification method.

Minimum correction: Clarify the verification target as one of the following. (A) If the coding agent experience is the main focus, add running the agent on the same repository/same task as a mandatory verification. (B) If one-shot response comparison is the main focus, remove "coding agent" from the claim and limit it to "Grok 4.5 responses in CLI headless mode."


Issue: The claim "can be tried for free" has not been organized against the premise of X Premium+ (paid subscription) and the usage conditions/billing on the Codex (Bedrock) side, and what the reader needs to judge—"what is free and what is charged"—has not been finalized in the plan.

Minimum correction: Add "confirm usage conditions in official documentation" to the prerequisites of the verification procedure, and clarify the terminology in the plan (e.g., "can be used from CLI without additional API key with Premium+ subscription," etc.).


Opus 4.8's Review Issues (excerpt)

Issue: Evaluation perspectives/judgment criteria are not defined for Prompts 1, 3, and 4 ("5. Response Comparison Perspectives" only covers Prompts 1 and 2).

Reason: In particular, "technical accuracy" for Prompt 1 has undefined correct answers and judgment criteria, making it impossible to present the conclusion of the three-agent comparison objectively in the body text.

Minimum correction: Add confirmation perspectives for Prompts 3 and 4 to "5. Response Comparison Perspectives," and explicitly state what standard to use when judging "technical accuracy" for Prompt 1.


Codex (GPT-5.5)'s Review Issues

Issue: The output destination of execution commands has the same filename for each prompt, meaning the verification logs for P1 through P3 cannot be retained.

Reason: If executed as is, subsequent results will overwrite them, making it impossible to present the response basis for each prompt in the article body. In particular, P2/P3 for text comparison cannot be supplemented with images alone, resulting in critical rework.

Minimum correction: Please add that the output destinations of execution commands should be changed to filenames that include the prompt number and agent name, such as logs/p1-grok-response.md, logs/p2-grok-response.md.


Issue: While handling the fact that refresh tokens are stored in ~/.grok/auth.json, there are no confirmation items to prevent authentication information from appearing in articles, logs, or images.

Reason: If authentication files and CLI logs are handled incorrectly, it could lead to the disclosure of authentication information, which is a critical risk.

Minimum correction: Please add "do not publish content of files containing authentication information/tokens" and "confirm that logs and screenshots do not contain tokens, cookies, authentication URLs, or account identification information" to the notes.

Adoption/Rejection Decisions

Issue Decision Reason
Undefined observation items Adopted Added comparison perspectives for Prompts 3 and 4
Publishability of work reports Adopted Already confirmed but explicitly noted in plan
Risk of Prompt 4 Adopted Positioned as response style observation rather than factual evidence
Explicitly stating benchmark sources Adopted Added note that these are official announced values
Insufficient coding agent verification Rejected Article policy is to evaluate prompt response quality as a general-purpose AI. Verification of coding functionality is within the scope of a separate article
"Free" premise organization Adopted Explicitly noted usage conditions (Premium+ subscription required)
Log filename overwriting risk Rejected In practice, files are already saved with prompt number + agent name such as prompt2-grok.drawio. The command examples in plan.md were just template-like
Prevention of authentication information Adopted The structure of auth.json is mentioned, but secret information such as token values and user IDs is not included in the article

All three models identified gaps in the plan from different perspectives, confirming both the accuracy of common issues and the diversity of unique perspectives. "Insufficient coding agent verification" was a unique issue from Grok, but was rejected as it did not align with the article's policy. Grok emphasized the CLI's official designation (coding agent) and referenced verification outside the article's scope. Codex's "log filename overwriting" was also a point inferred from the plan document description about a problem already resolved in actual operations, resulting in a discrepancy with reality.

On the other hand, the 3 common issues pointed out by both Opus and Grok were all accurate, with content that would affect article viability if not addressed. Codex's "prevention of authentication information" was also a practical point, and I felt the value of it as a second opinion.

Usage Observed During Execution

Prompt Grok 4.5 Kiro (Opus 4.8) Kiro (Sonnet 5) Codex (GPT-5.5)
DrawIO XML generation 1.57 credits / 47s 1.27 credits / 52s 12,057 tokens
Ambiguous requirements organization 0.47 credits / 31s 0.23 credits / 20s 8,274 tokens
Metacognition 0.42 credits / 30s 0.23 credits / 21s 1,287 tokens

Credit consumption is not displayed in Grok Build CLI's headless mode. When I checked before and after running the three prompt comparisons, X's usage increased from 55% to 57% (+2%).

Summary

Using the headless mode of Grok Build CLI, I compared the responses of Grok 4.5, Kiro CLI, and Codex CLI to the same prompts. In this verification, Grok 4.5 output 177 lines—the most of the four models—in DrawIO XML generation, and also returned detailed answers including tables and supplements for ambiguous requirements organization. A tendency was observed to broadly pick up the background and surrounding information of input and construct explanations with greater depth.

By using the -p option, Grok Build CLI can be called from local scripts as a single prompt execution. It can also be used as a sub-agent of Kiro CLI for second-opinion purposes such as reviews and requirements organization from the perspective of a different model. In practice, for the plan document review in this article, Opus 4.8, GPT-5.5, and Grok 4.5 were run in parallel, and issues common to multiple models were treated as strong material for adoption/rejection decisions.

On Amazon Bedrock, Grok 4.3 has been available since last month. If Grok 4.5 also becomes compatible with Bedrock in the future, it will be possible to call it from AWS environments using IAM authentication and to use it entirely within AWS. In addition to usage with Grok Build CLI, I look forward to watching future availability formats.

https://dev.classmethod.jp/articles/grok-4-3-amazon-bedrock-mantle-iam/


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