Claude Fable 5.1 Text Generation API
anthropic/claude-fable-5.1Claude Fable 5.1 Text Generation turns text and image context into code, research findings, and detailed answers for long-running work. Its 1M-token context window and adaptive reasoning help carry requirements and evidence across connected steps.
Claude Fable 5.1
Anthropic · chat-completions
Quick start
Send a POST request to /v1/messages with anthropic/claude-fable-5.1. Choose JSON or SSE with stream, and receive generated content and usage.
- Endpoint
- POST /v1/messages
- Model ID
- anthropic/claude-fable-5.1
- Protocol
- Claude Messages
Request fields
| Field | Requirement | Description |
|---|---|---|
| model | Required | anthropic/claude-fable-5.1 |
| messages | Required | A non-empty ordered conversation array; each message has role and content. |
| max_tokens | Required | A positive integer setting the maximum output tokens for this response. |
| system | Optional | System instructions as a string or text blocks. |
| temperature | Optional | Sampling temperature; the playground allows 0–2. |
| top_p | Optional | Nucleus sampling probability; the playground allows 0–1 and defaults to 1. |
| cache_control | Optional | Places a prompt-cache marker on cacheable content. |
| stream | Optional | Returns an SSE event stream when true. |
Response and usage
Successful responses include generated content and usage. Billing settles from actual input, output, and cache tokens.
Streaming
Set stream: true to read SSE. Finalize usage accounting from the terminal usage event.
curl --request POST \
--url https://api.vidgo.ai/v1/messages \
--header "x-api-key: $VIDGO_API_KEY" \
--header 'anthropic-version: 2023-06-01' \
--header 'Content-Type: application/json' \
--data '{
"model": "anthropic/claude-fable-5.1",
"messages": [
{
"role": "user",
"content": "Explain why deterministic retries matter in distributed systems."
}
],
"max_tokens": 1024,
"temperature": 1,
"top_p": 1,
"stream": false
}'Keep API keys on the server. Never expose them in browser code or public repositories.
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Claude Fable 5.1 Text Generation API frequently asked questions
What is the Claude Fable 5.1 Text Generation API?
Claude Fable 5.1 Text Generation is an Anthropic model for long-running coding, research, and complex knowledge work. It turns text and image context into code, analysis, and detailed answers while tracking requirements across connected steps. Its 1M-token context window and adaptive reasoning support extensive source material and multistep work. You can call it programmatically or try it from the playground above.
How does Claude Fable 5.1 handle long-running coding?
Claude Fable 5.1 can work across connected coding tasks, including multi-file features, refactors, debugging, and review. Provide the relevant repository files, target behavior, and test results so each step can be checked against the same requirements.
How much context can Claude Fable 5.1 analyze?
Claude Fable 5.1 has a 1,000,000-token context window. Include the relevant documents, source files, and instructions in the conversation when the task depends on their relationships.
How many output tokens can Claude Fable 5.1 generate?
The model specification allows up to 128,000 output tokens. Set max_tokens for the API response; the on-page Playground provides a 256–8,192-token control for interactive trials.
How does Claude Fable 5.1 interpret charts and diagrams?
Claude Fable 5.1 combines image and text input to analyze charts, diagrams, tables, and dense documents. In Claude Messages, place supported image blocks in messages.content and ask a specific question about the visual evidence.
How does Claude Fable 5.1 use adaptive reasoning?
Claude Fable 5.1 uses adaptive thinking with high effort by default. Describe the decision, constraints, and evidence clearly so the model can devote its reasoning to the parts of the task that need it.
How can Claude Fable 5.1 reuse prompt context?
Claude Fable 5.1 can read cached prompt content across repeated requests. Use cache_control on stable instructions or reference material in Claude Messages, then keep that content unchanged when continuing the workflow.