I tested the re-released "Claude Fable 5" on Amazon Bedrock
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Introduction
On June 12, 2026, access to Claude Fable 5 and Mythos 5 was suspended due to U.S. government export controls. After approximately three weeks of interruption, the export controls were lifted on June 30, and service resumed on July 1.
According to Anthropic's official blog, the suspension occurred as follows: Amazon researchers reported a method for bypassing Fable 5's safeguards, prompting the U.S. government to apply export controls. Anthropic consulted with the government, trained a new safety classifier, and improved the system to block the reported method in over 99% of cases.
This article verifies the operation on Amazon Bedrock after service resumption and examines changes in regional deployment compared to the previous article (as of 2026-06-10).
Changes from the Previous Article (6/10)
| Item | Previous Article (6/10) | Current (7/1) |
|---|---|---|
| Model Status | ACTIVE → Suspended on 6/12 | ACTIVE |
| Model Availability Regions (ACTIVE) | us-east-1, eu-north-1 | us-east-1, us-east-2, us-west-2, eu-west-1, ap-northeast-1 |
| US Inference Profile Routing Destinations | Unconfirmed | us-east-1, us-east-2, us-west-2 |
| Mantle Support | Outside verification scope | Cannot be invoked within verification scope (404 in all regions) |
| Safeguards | Initial version | New safety classifier added (blocks reported method in over 99% of cases) |
Verification Details
The verification environment is as follows.
- Regions: us-east-1 (Converse API), ap-northeast-1 (Global profile attempt)
- Model ID:
us.anthropic.claude-fable-5(US cross-region inference profile) - Verification Date/Time: 2026-07-01 15:50 JST
- Prerequisites: Agreement / Data Retention configured in the previous article
Confirming Regional Deployment
Model availability was confirmed in each region using list-foundation-models. Below is an example executed in us-east-1. The --region flag was switched to run in each region.
aws bedrock list-foundation-models \
--query "modelSummaries[?contains(modelId, 'fable')].{modelId:modelId,status:modelLifecycle.status}" \
--output table \
--region us-east-1
While the previous article showed only two regions (us-east-1 and eu-north-1), the model was now ACTIVE in five regions.
| Region | Status |
|---|---|
| us-east-1 | ACTIVE |
| us-east-2 | ACTIVE |
| us-west-2 | ACTIVE |
| eu-west-1 | ACTIVE |
| ap-northeast-1 | ACTIVE |
The routing destinations for the US inference profile were also confirmed.
aws bedrock list-inference-profiles \
--query "inferenceProfileSummaries[?contains(inferenceProfileId, 'fable')]" \
--region us-east-1
The US profile (us.anthropic.claude-fable-5) routes to three regions: us-east-1, us-east-2, and us-west-2. A Global profile (global.anthropic.claude-fable-5) also exists, but as described later, its operation could not be confirmed at the time of verification.
Running Inference with the Converse API
US Profile (Success)
aws bedrock-runtime converse \
--model-id "us.anthropic.claude-fable-5" \
--messages '[{"content":[{"text":"Hello! Reply with exactly one sentence confirming your model name."}],"role":"user"}]' \
--inference-config '{"maxTokens":100}' \
--region us-east-1
Full Response
{
"output": {
"message": {
"role": "assistant",
"content": [
{
"reasoningContent": {
"reasoningText": {
"text": "",
"signature": "CAISiAIKYAgPEAEYAipA..."
}
}
},
{
"text": "I am Claude, an AI assistant made by Anthropic."
}
]
}
},
"stopReason": "end_turn",
"usage": {
"inputTokens": 28,
"outputTokens": 49,
"totalTokens": 77,
"cacheReadInputTokens": 0
},
"metrics": {
"latencyMs": 2534
}
}
The Converse API call via the US profile succeeded. The response contained both reasoningContent and text, as in the previous article. Latency was 2,534ms, and outputTokens: 49 (higher than the visible text would suggest, as tokens for reasoningContent are included).
Global Profile (Could Not Confirm Success at Verification Time)
Two types of errors were observed with the Global profile.
When called from us-east-1:
An error occurred (InternalServerException) when calling the Converse operation (reached max retries: 2):
The system encountered an unexpected error during processing. Try your request again.
Three attempts were made in total (including automatic SDK retries), all resulting in the same InternalServerException.
When called from ap-northeast-1:
An error occurred (ValidationException) when calling the Converse operation:
The model returned the following errors: data retention mode 'default' is not available for this model
Regarding the InternalServerException, all three attempts under the same conditions failed, and the cause could not be isolated at the time of verification. The ValidationException is an error related to Data Retention settings, but the cause could not be identified from this verification alone.
Mantle (Anthropic-Compatible Endpoint)
Invocation via Bedrock Mantle (/anthropic/v1/messages), which was outside the verification scope in the previous article, was tested.
from anthropic import AnthropicBedrockMantle
client = AnthropicBedrockMantle(aws_region='us-east-1')
response = client.messages.create(
model='anthropic.claude-fable-5',
max_tokens=64,
messages=[{'role': 'user', 'content': 'Hello! Reply in one sentence.'}]
)
anthropic.NotFoundError: Error code: 404 -
{'type': 'error', 'error': {'type': 'not_found_error',
'message': "The model 'anthropic.claude-fable-5' does not exist"}}
The following combinations of regions and model ID patterns were tested, all returning 404.
| Region | Result |
|---|---|
| us-east-1 | 404 |
| us-west-2 | 404 |
| us-east-2 | 404 |
| eu-west-1 | 404 |
| ap-northeast-1 | 404 |
Model IDs tested: anthropic.claude-fable-5, claude-fable-5, us.anthropic.claude-fable-5, global.anthropic.claude-fable-5
At the time of verification, Fable 5 could not be invoked via Bedrock Mantle using any of the tested region and model ID combinations. Using the Converse API (bedrock-runtime) is required.
Summary
It was confirmed that Claude Fable 5 has resumed availability on Amazon Bedrock. Inference execution via the US inference profile (us.anthropic.claude-fable-5) succeeded using the Converse API from us-east-1.
Regional deployment had expanded from two regions at the time of the previous article to five regions, as shown by list-foundation-models. The US inference profile routing destinations were also confirmed as three regions: us-east-1, us-east-2, and us-west-2.
On the other hand, while the Global profile exists, its operation could not be confirmed in this verification, and Bedrock Mantle also returned 404 in all tested cases. As of this writing, the only confirmed working method in this verification is invoking the US inference profile via the Converse API from us-east-1.
