ToAPIs

Quick Answer

  • Built for complex, long-horizon coding tasks and high-value engineering workflows.
  • Strong instruction adherence and consistency make it suitable for strict delivery requirements.
  • Supports vision understanding, tool calling, and streaming for practical multimodal pipelines.

Key Parameters

  • model | string | required | claude-opus-4-6 | - | Model identifier for this page (for example claude-opus-4-6).
  • messages | object[] | required | - | - | Conversation messages in chronological order; role support is user and assistant.
  • max_tokens | integer | required | - | >=1 | Maximum output tokens.
  • system | string | object[] | optional | - | - | Top-level system prompt (do not place it inside messages).
  • stream | boolean | optional | false | - | Whether to enable SSE streaming output.
  • temperature | number | optional | 1 | 0-1 | Sampling temperature controlling output randomness.
  • top_p | number | optional | - | 0-1 | Nucleus sampling threshold; avoid aggressively tuning with temperature together.
  • stop_sequences | string[] | optional | - | - | Stop sequences to end generation on matching substrings.
  • Authorization | HTTP Header | optional | - | - | Bearer auth: Authorization: Bearer <YOUR_API_KEY>.
  • x-api-key | HTTP Header | optional | - | - | API key auth (common in Anthropic SDK workflows), use either this or Authorization.
  • anthropic-version | HTTP Header | optional | 2023-06-01 | - | Anthropic API version header; usually set automatically by Anthropic SDK.

Common Errors

  • 400 invalid_request_error: trigger=Missing fields, invalid messages schema, or mismatched parameter types.; fix=Validate model, messages, and max_tokens fields and data types.; retry=Retry only after fixing payload.
  • 401 authentication_error: trigger=Missing Authorization header, invalid format, or invalid key.; fix=Verify bearer token format and key permissions.; retry=Retry after auth is fixed.
  • 429 rate_limit_exceeded: trigger=Request rate, concurrency, or current quota hits upstream rate limiting.; fix=Apply exponential backoff first, then review request rate, concurrency, and quota usage.; retry=Use 1s/2s/4s backoff with jitter; if it persists, reduce submission pressure.
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Model Guide

Claude Opus 4 6

Model ID: claude-opus-4-6

Vendor: AnthropicModalities: ChatPrice: Input $2.00/1M, Output $10.00/1MUpdated: 2026-05-02

Claude Opus 4 6 is a high-end Claude model for complex software engineering and multi-step reasoning workflows. This guide focuses on practical API integration patterns and production-oriented parameter usage. For model limits and release details, refer to official documentation.

Open in PlaygroundDocs

Model Overview

Quick Answer

  • Built for complex, long-horizon coding tasks and high-value engineering workflows.
  • Strong instruction adherence and consistency make it suitable for strict delivery requirements.
  • Supports vision understanding, tool calling, and streaming for practical multimodal pipelines.

Claude Opus 4 6 Model Features

Core Section

Core capabilities and practical engineering value

Complex engineering problem solving

Well-suited for cross-module refactors, difficult debugging, and constrained code delivery tasks.

Long-running task consistency

Maintains stable execution across multi-step flows and checks key outcomes before completion.

High-fidelity instruction following

Handles strict system constraints and task requirements for low-tolerance production processes.

Vision + technical output quality

Useful for interface reviews, technical documentation, and other multimodal engineering artifacts.

Tool calling and streaming

Supports Messages + tools + input_schema and stream=true for plan-execute-review workflows.

Production integration readiness

Can be integrated through claude-opus-4-7 in API workflows and enterprise deployment pipelines.

How to Use Claude Opus 4 6 API

  1. Create an API key and set Authorization: Bearer <YOUR_API_KEY>.
  2. Send POST requests to /v1/messages with Content-Type: application/json.
  3. Include model, messages, and max_tokens at minimum; add system constraints for coding tasks.
  4. For tool use, pass tools with input_schema, execute tool_use results, then continue the next turn.
  5. For real-time output, set stream=true and assemble incremental SSE events.
  6. Finalize by stop_reason: stop means complete, tool_use means continue tool execution flow.
Claude Opus 4 6

When to Use

  • When you need complex architecture planning, cross-module refactoring, or difficult debugging support.
  • When long-running workflows require stable execution and consistency checks before output.
  • When your workflow combines code reasoning with image understanding or multimodal review tasks.

Runtime Behavior

  • Messages endpoint is POST /v1/messages, following ToAPIs docs conventions.
  • With stream=true, responses are returned as SSE events such as message_start, content_block_delta, and message_stop.
  • Function calls are emitted via tool_use blocks; stop_reason is typically tool_use in tool workflows.
  • Calls are stateless; multi-turn context must be provided explicitly in messages by your application.
Claude Opus 4 6

Key Parameters

ParameterTypeRequiredDefaultRangeDescription
modelstringYesclaude-opus-4-6-Model identifier for this page (for example claude-opus-4-6).
messagesobject[]Yes--Conversation messages in chronological order; role support is user and assistant.
max_tokensintegerYes->=1Maximum output tokens.
systemstring | object[]No--Top-level system prompt (do not place it inside messages).
streambooleanNofalse-Whether to enable SSE streaming output.
temperaturenumberNo10-1Sampling temperature controlling output randomness.
top_pnumberNo-0-1Nucleus sampling threshold; avoid aggressively tuning with temperature together.
stop_sequencesstring[]No--Stop sequences to end generation on matching substrings.
AuthorizationHTTP HeaderNo--Bearer auth: Authorization: Bearer <YOUR_API_KEY>.
x-api-keyHTTP HeaderNo--API key auth (common in Anthropic SDK workflows), use either this or Authorization.
anthropic-versionHTTP HeaderNo2023-06-01-Anthropic API version header; usually set automatically by Anthropic SDK.

Common Errors

400 invalid_request_error

Trigger: Missing fields, invalid messages schema, or mismatched parameter types.

Fix: Validate model, messages, and max_tokens fields and data types.

Retry: Retry only after fixing payload.

401 authentication_error

Trigger: Missing Authorization header, invalid format, or invalid key.

Fix: Verify bearer token format and key permissions.

Retry: Retry after auth is fixed.

429 rate_limit_exceeded

Trigger: Request rate, concurrency, or current quota hits upstream rate limiting.

Fix: Apply exponential backoff first, then review request rate, concurrency, and quota usage.

Retry: Use 1s/2s/4s backoff with jitter; if it persists, reduce submission pressure.

FAQ

What is Claude Opus 4 6 best for in engineering workflows?

It is best for high-complexity, high-value tasks such as difficult coding problem solving, long-horizon refactors, and quality-sensitive delivery reviews.

What is the fastest API integration path?

Prepare an API key, authenticate with Authorization: Bearer, then POST to /v1/messages with model, messages, and max_tokens.

How should tool calling be integrated?

Pass tools with input_schema, execute returned tool_use calls, and send tool results back for the next completion turn.

How should streaming be handled?

Set stream=true and process SSE events incrementally, especially content_block_delta and final stop_reason handling.

Mode Notes

Chat Completions with Claude Opus 4 6

OpenAI-compatible entry for low-friction migration from existing coding assistants and SDK flows.

Mode Parameters

modelmessagestemperaturemax_tokensstream

Best Scenarios

  • Code generation and completion
  • Error analysis and fix suggestions
  • PR summary generation

Anthropic Messages with Claude Opus 4 6

Anthropic-native message interface for coding agents and tool orchestration.

Mode Parameters

modelmessagessystemmax_tokenstoolstool_choice

Best Scenarios

  • Code review assistant
  • Repository Q&A agent
  • Automated remediation pipeline

Streaming with Claude Opus 4 6

Enable stream for incremental output in IDE and terminal coding experiences.

Mode Parameters

streammessagesmax_tokensstop

Best Scenarios

  • Real-time IDE suggestions
  • Token-by-token terminal output
  • Early partial code rendering

Tool Calling with Claude Opus 4 6

Declare tools with input_schema to trigger testing, retrieval, and execution actions.

Mode Parameters

toolstools[].input_schematool_choicemessagesmax_tokens

Best Scenarios

  • Run tests and explain failures
  • Patch code after repository retrieval
  • Multi-step engineering agents

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