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Claude Sonnet 5.5
Anthropic's balanced model for agentic coding and knowledge work. Text and image input, 1M context, 128K output including thinking, and high default effort. Supports adaptive thinking or between_tools at high effort or below. Custom function tools are supported on Chat Completions and Messages endpoints; forced tool choice is not supported.
Web Search
Web Fetch
Code Execution
Specifications
| Provider | Anthropic |
| Category | Text |
| Context window | 1M tokens |
Pricing (Starter tier)
260.00 credits / 1M input tokens
26.00 credits / 1M cached input tokens
325.00 credits / 1M cache-write tokens (5 minutes)
1,300.00 credits / 1M output tokens
Higher tiers get volume discounts. See tiers
Quick Start
curl -N https://query.genx.sh/v1/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"claude-sonnet-5-5","messages":[{"role":"user","content":"Review this function for bugs: function median(a) { a.sort(); return a[a.length / 2]; }"}],"max_tokens":8192,"reasoning_effort":"medium","stream":true}'
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
prompt |
string | required | — | The input text prompt |
system_prompt |
string | optional | — | System instructions |
image_url |
string | optional | — | Image URL to analyze |
max_tokens |
number | optional | 128000 |
Maximum output tokens including thinking, up to 128000 |
effort |
string | optional | high |
low, medium, high, xhigh, or max. between_tools supports only low, medium, or high. |
thinking |
object | optional | — | Omit or use type adaptive, optionally with display omitted, summarized, or updates. The alternative {type: between_tools} accepts no other fields. Disabled thinking and manual budgets are unsupported. |
tools |
array | optional | — | Built-in web_search, web_fetch, and code_execution. Code execution requires web_search or web_fetch version 20260209 or newer alongside it. Queue sessions do not support custom function tools. |
Availability
Claude Sonnet 5.5 is available in the GenX Pro App and via the GenX Router API.