Claude Fable 5

AnthropicMCP Tool CallReasoning

anthropic/claude-fable-5Closed API

Claude model for creative writing, analysis, and controlled agent workflows

Benchmark Pricing$10.00 / 1M in$50.00 / 1M out$1.00 cache read

Context: 1,000,000 tokens•Max Output: 128,000 tokens•Knowledge: 2026-01-31•Released: 2026-06-09

TECHNICAL SPECIFICATIONS

Context Window1,000,0001M tokens

Max Output128,000128K tokens

LicenseProprietaryCloud API only

Input Modalities

TextVisionPDF

Function / Tool CallingSupported (MCP Ready)

Structured OutputsGuaranteed Schema

MODEL CONTEXT PROTOCOL (MCP) READINESS

✓ Claude Fable 5 natively supports OpenAI / Anthropic format tool calling and is fully compatible with MCP servers and agent loops.

MCP Context Window Recommendations

With a context capacity of 1,000,000 tokens, this model can handle extremely large MCP resource manifests, complete database schemas, and multiple active server tool definitions simultaneously without degradation.

STANDARDIZED BENCHMARKS & EVALS

SWE-Bench Proresolve rate

80.3

SWE-Bench Verifiedresolved

Terminal-Benchsuccess rate

Humanity's Last Examaccuracy

64.5

OSWorld-Verifiedsuccess rate

FrontierCodepass rate

29.3

GDPval-AAElo

1932

AutomationBenchsuccess rate

17.4

API CALL INVOCATION EXAMPLE

// Example: Calling Claude Fable 5 via OpenAI SDK
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.ANTHROPIC_API_KEY,
});

const response = await client.chat.completions.create({
  model: "anthropic/claude-fable-5",
  messages: [{ role: "user", content: "Hello! Can you inspect MCP tools?" }],
});

console.log(response.choices[0].message.content);