claude-fable-5-1 — API, Pricing & Context Window | Vivgrid

claude-fable-5-1 is Anthropic's most capable model and sits above the Opus tier for the most demanding reasoning and long-horizon agentic work. It pairs a 1M-token context window with 128K-token max output and always-on adaptive thinking, so a single request can plan, execute, and verify work that would otherwise need several passes.

On Vivgrid, claude-fable-5-1 is geo-distributed across AMER, EMEA, and APAC and reachable on both the native Messages API (/messages) and Chat Completions (/chat/completions) with one unified key, so switching an agent from claude-opus-5 is a model-string change whichever surface you already use.

Specifications

Pricing

Pricing in USD per 1M tokens, matching the provider's rates.

What one request costs

The rates above applied to a 20K-token prompt with a 2K-token reply — a typical single agent turn, small enough that every request is billed at the base rate.

Prompt caching is billed at $12.50 per 1M cache-write tokens on the 5-minute TTL and $20.00 per 1M on the 1-hour TTL, with cached reads at $0.50 — half the cache-read rate of claude-fable-5.

API surfaces

The Vivgrid Console catalogs claude-fable-5-1 on 2 surfaces, all behind the same API key. The endpoint shown is the one the Console previews for that surface.

Quick start

Get an API key from the Vivgrid Console, then call claude-fable-5-1 directly.

curl https://api.vivgrid.com/v1/chat/completions \
  -H "Authorization: Bearer $VIVGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-fable-5-1",
    "messages": [
      { "role": "user", "content": "Say hello in English, Chinese and Spanish." }
    ],
    "stream": true
  }'

curl https://api.vivgrid.com/v1/messages \
  -H "Authorization: Bearer $VIVGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-fable-5-1",
    "max_tokens": 1024,
    "messages": [
      { "role": "user", "content": "Say hello in English, Chinese and Spanish." }
    ],
    "stream": true
  }'

Choosing within the Claude 5 family

Prices are USD per 1M tokens at the base rate. Rows marked this page are the model described here.

Ideal use cases

• Long-horizon coding agents that run for many turns without supervision
• Whole-repository migrations and refactors inside a single 1M-token pass
• High-stakes reasoning where answer quality outweighs token cost
• Deep research and analysis chaining many tool calls per session

Related models

• claude-fable-5 — the prior Fable release at the same per-token price
• claude-opus-5-5 — the latest Opus model at a lower price
• gpt-6-astra — OpenAI's frontier gpt-6 coding model