Claude Opus 5.5 now available on AI Gateway
Claude Opus 5.5 from Anthropic is now available via Vercel's AI Gateway with improved agentic coding, long-context reasoning, and a 1M-token context window. The model includes two breaking API changes: adaptive thinking (no longer allows disabling thinking or fixed budgets) and removal of forced tool use in favor of structured outputs.
from is now available on . It is a step-change improvement over , with its biggest gains in agentic coding, long-running agent tasks, and knowledge work.Claude Opus 5.5AnthropicAI GatewayOpus 5
Opus 5.5 is also a better collaborator over long runs. It reports back in plain language on what it did, what it found, and what it needs next, making it easier to supervise work that spans many steps or takes place over a longer period.
Opus 5.5 includes two API changes that can turn previously valid requests into HTTP 400 errors:
Use across the , , , and connected to AI Gateway. You can also enable with the gateway option r . The model has a 1M-token context window, returns up to 128K tokens, and has a June 2026 knowledge cutoff. anthropic/claude-opus-5.5speedanthropic/claude-opus-5.5-fastAI SDKOpenAI-compatible Chat Completions APIAnthropic Messages APIcoding agentsfast mode
and are opt-in request controls. This example pins inference to the US and ZDR:Regional inferenceZero Data Retention
Install the latest and connect your supported coding agents to AI Gateway:Vercel CLI
Then select in the agent. In , use to toggle fast mode for the session. See the for other agent-specific instructions.anthropic/claude-opus-5.5/fastClaude Codecoding agents guide
AI Gateway provides a unified API for calling models, tracking usage and cost, and configuring retries, failover, and performance optimizations for higher-than-provider uptime. It includes built-in , , , and more.custom reportingbudgets for API keysrouting rules
AI Gateway reflects provider pricing with no markup and does not charge a platform fee on inference, including on (BYOK) requests.Bring Your Own Key
Try , or available on AI Gateway.Claude Opus 5.5 in the model playgroundview all language models
Requests that disable thinking or set a fixed thinking budget are rejected. The model decides how much to think for each request. Use effort and prompting to steer its thinking behavior.Thinking is always adaptive.
Requests cannot require a tool call or force a specific tool. Prompt the model toward the tool, then catch and retry misses in your harness. If you previously forced a tool call to return JSON, use structured outputs instead.Forced tool use is retired.
Regional inference and Zero Data Retention
Use Opus 5.5 in coding agents
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