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Claude Fable 5.1
Send a message to test this OpenAI-compatible chat completions model.
Explore different use cases and parameter configurations
Transparent pricing with no hidden fees. Pay as you go.
| Rule & Modality | Channel | Credits | Price (USD) | Official / Reference Price | Daily Savings |
|---|---|---|---|---|---|
Claude Fable 5.1 regular pricing textAnthropicToken | Regular | Input1,100.11 Output5,500.55 Cache read27.50 Cache write 5m1,375.14 Cache write 1h2,200.22 credits / 1M tokens | Input: $5.0005 Output: $25.003 Cache read: $0.125 Cache write 5m: $6.251 Cache write 1h: $10.001 per 1M tokens | - | - |
Complete guide to using claude-fable-5-1
Build coding assistants, research applications, and knowledge-work tools with Claude Fable 5.1 through the OpenAI-compatible ApiPass chat completions endpoint. Send chat messages, tune optional reasoning effort, and receive a standard chat completion or streamed response.
Claude Fable 5.1 is presented as a model for extended coding, multi-step research, complex reasoning, and professional knowledge work. It can help with debugging, code review, large refactors, analysis, and drafting practical deliverables. On ApiPass, use model claude-fable-5-1 with POST /v1/chat/completions. Provide a non-empty messages array containing role and content in each message; no asynchronous task workflow is required for this endpoint.
Build assistants for multi-file development, debugging, code review, migrations, and refactoring. Supply relevant code and instructions as chat messages.
Use the model to analyze supplied information, connect findings, and draft summaries or other practical outputs. Provide source material in messages when you need it considered.
Send requests to /v1/chat/completions and read non-streaming replies from choices[0].message.content. Set stream to true for Server-Sent Event chunks ending with data: [DONE].
The supplied content highlights extended development sessions, including debugging, code review, migrations, and large refactors. Structure each request with the context the assistant needs for the next step.
Apply the model to complex questions and knowledge-intensive work, from research synthesis to analysis of text extracted from reports, tables, or other materials.
The ApiPass chat route accepts reasoning_effort values low and high. Use this optional field to request an effort level appropriate to the task; provider behavior may vary.
Create assistants that examine supplied code, identify edge cases, propose fixes, and help plan multi-file changes.
Build applications that turn supplied notes and source material into concise findings, open questions, and actionable summaries.
Assist with document analysis, reporting, business research, and drafting documents or presentation outlines from provided information.
The supplied content emphasizes improvements for long-horizon work compared with Fable 5. Choose a workflow based on the context and depth your application needs.
The source describes Claude Fable 5.1 as better suited to maintaining progress through extended coding sessions and addressing root causes. Include relevant repository context and verify proposed changes before applying them.
The source highlights deeper research and turning complex analysis into usable outputs. For dependable results, provide the underlying material in chat messages and review factual claims.
The supplied content describes flexible, usage-based pricing but provides no verified per-token rate. Check current ApiPass pricing before estimating production costs.
Non-streaming chat completions include usage.prompt_tokens, usage.completion_tokens, and usage.total_tokens. Use these fields to monitor consumption.
The source mentions credits for eligible new users. Check your ApiPass account for current availability and test representative coding or research prompts before production rollout.
Test a chat request using model claude-fable-5-1 and a non-empty messages array. Try coding, research, or summarization prompts relevant to your application.
Create an ApiPass API key and review the chat completions request parameters. Send the key in an Authorization: Bearer header.
POST your JSON request to https://api.apipass.dev/v1/chat/completions. Read the assistant reply from choices[0].message.content, or set stream to true to process event-stream chunks.
Evaluate responses, monitor token usage, and add optional parameters such as max_tokens or reasoning_effort when your workflow needs them.
All APIs require authentication via Bearer Token.
Authorization: Bearer
Generate text with claude-fable-5-1 through the ApiPass OpenAI-compatible chat completions endpoint.
Send an OpenAI-compatible JSON request body. ApiPass routes claude-fable-5-1 to the APIPASS adapter, which forwards the chat payload to APIPASS's LLM endpoint.
1{
2 "model": "claude-fable-5-1",
3 "messages": [
4 {
5 "role": "user",
6 "content": "Hello!"
7 }
8 ],
9 "stream": false,
10 "temperature": 0.7,
11 "max_tokens": 512,
12 "channel": "auto"
13}modelRequiredstringThe public ApiPass model name. The APIPASS adapter also accepts the gpt-5.5 alias and maps it upstream to claude-fable-5-1.
"claude-fable-5-1"
messagesRequiredarray<object>OpenAI-style chat messages array. The adapter requires a non-empty list, and each message object must include role and content.
[{"role":"user","content":"Write a short product announcement for APIPASS Claude Fable 5.1 support in ApiPass."}]streamOptionalbooleanSet to true to receive Server-Sent Events. When false or omitted, ApiPass returns a single OpenAI-compatible chat.completion response.
false
temperatureOptionalnumberOptional sampling temperature from 0 to 2. If omitted, the adapter does not include temperature in the upstream request.
Allowed range: 0 to 2
0.7
max_tokensOptionalintegerOptional maximum number of completion tokens. If omitted, the upstream provider decides the response length.
Must be greater than 0 when provided
512
top_pOptionalnumberOptional nucleus sampling value accepted by the ApiPass chat endpoint and forwarded to APIPASS when supplied.
Allowed range: 0 to 1
0.9
frequency_penaltyOptionalnumberOptional OpenAI-compatible frequency penalty accepted by ApiPass and forwarded when supplied.
Allowed range: -2 to 2
0
presence_penaltyOptionalnumberOptional OpenAI-compatible presence penalty accepted by ApiPass and forwarded when supplied.
Allowed range: -2 to 2
0
response_formatOptionalobjectOptional response format object accepted by the ApiPass chat endpoint and forwarded to the provider if present.
{"type":"json_object"}toolsOptionalarray<object>Optional OpenAI-compatible tools array. ApiPass accepts tool definitions and forwards them to APIPASS when supplied; support depends on the upstream model.
[{"type":"function","function":{"name":"lookup_order","description":"Look up an order by ID","parameters":{"type":"object","properties":{"order_id":{"type":"string"}},"required":["order_id"]}}}]include_thoughtsOptionalbooleanOptional provider-specific flag accepted by ApiPass and forwarded when true.
false
reasoning_effortOptionalstringOptional reasoning effort value accepted by the ApiPass chat endpoint and forwarded to the provider when supplied.
Available options:
"low"
_provider_config_idOptionalstringOptional ApiPass routing override. Supply a provider_model_configs.id to force this request to a specific configured APIPASS provider.
"provider-config-id"
channelOptionalstringYou may specify the corresponding provider within APIPASS via the channel parameter; these providers handle the actual image and video generation tasks. APIPASS currently offers three provider options:
The default value for the channel parameter is auto. When enabled, APIPASS automatically allocates tasks across available providers based on real-time pricing and stability metrics to balance minimal cost and reliable performance. Retain the default auto value unless you have custom routing requirements.
Available options:
auto
Each item in the messages array follows the OpenAI chat message shape validated by ApiPass before the APIPASS adapter is called.
messages[].roleRequiredstringMessage role. ApiPass accepts developer, system, user, and assistant roles in the chat request model.
Available options:
"user"
messages[].contentRequiredstringMessage content. For Claude Fable 5.1 text generation, use plain text content for the most predictable provider behavior.
"Summarize the following text in three concise bullets."
1curl -X POST "https://api.apipass.dev/v1/chat/completions" \
2 -H "Content-Type: application/json" \
3 -H "Authorization: Bearer YOUR_API_KEY" \
4 -d '{
5 "model": "claude-fable-5-1",
6 "messages": [
7 {
8 "role": "system",
9 "content": "You are a precise and concise assistant."
10 },
11 {
12 "role": "user",
13 "content": "Write a short product announcement for APIPASS Claude Fable 5.1 support in ApiPass."
14 }
15 ],
16 "temperature": 0.7,
17 "max_tokens": 512,
18 "stream": false
19 }'1{
2 "id": "chatcmpl_gpt_5_5_demo",
3 "object": "chat.completion",
4 "created": 1765968190,
5 "model": "claude-fable-5-1",
6 "choices": [
7 {
8 "index": 0,
9 "message": {
10 "role": "assistant",
11 "content": "ApiPass now supports APIPASS Claude Fable 5.1 through the standard OpenAI-compatible chat completions endpoint."
12 },
13 "finish_reason": "stop"
14 }
15 ],
16 "usage": {
17 "prompt_tokens": 35,
18 "completion_tokens": 19,
19 "total_tokens": 54
20 }
21}idApiPass chat completion response ID.
objectResponse object type. Non-streaming calls return chat.completion.
modelThe public model name used for the request.
choices[0].message.contentAssistant reply text extracted from the APIPASS OpenAI-compatible response.
choices[0].finish_reasonCompletion finish reason. ApiPass returns stop for successful non-streaming Claude Fable 5.1 completions.
usage.prompt_tokensPrompt token count reported by the upstream provider.
usage.completion_tokensCompletion token count reported by the upstream provider.
usage.total_tokensTotal token count used for ApiPass usage accounting.
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