1,300 pages for code.
Titles and paths first, then pages whose text carries it. Each row opens that page as this site last read it.
overview
Claude Developer Platform · in the page
models/opus-5-5/overview
…0 USD per million input / output tokens. Four breaking changes affect code already running on Claude Opus 5: [thinking can't be disabled](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-…
whats-new-opus-5-5
Claude Developer Platform · in the page
models/opus-5-5/whats-new-opus-5-5
…0 USD per million input / output tokens. Four breaking changes affect code already running on Claude Opus 5: [thinking can't be disabled](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-…
overview
Claude Developer Platform · in the page
models/opus-5/overview
…| * **Context:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 20…
Models overview
Claude Developer Platform · in the page
models/overview
…vel. * **Context window:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 20…
overview
Claude Developer Platform · in the page
models/sonnet-4-5/overview
…| * **Context:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 20…
overview
Claude Developer Platform · in the page
models/sonnet-4-6/overview
…| * **Context:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 20…
migration-guide
Claude Developer Platform · in the page
models/sonnet-5-5/migration-guide
…s, and a checklist for each starting model. --- This guide lists the code changes for moving to Claude Sonnet 5.5 from Claude Sonnet 5, Claude Sonnet 4.6, Claude Sonnet 4.5, Claude Sonnet 4, Claude 3…
overview
Claude Developer Platform · in the page
models/sonnet-5-5/overview
…t combination of speed and intelligence. Five breaking changes affect code already running on Claude Sonnet 5: * [Turn off up-front thinking with `between_tools`](https://platform.claude.com/docs/en/…
whats-new-sonnet-5-5
Claude Developer Platform · in the page
models/sonnet-5-5/whats-new-sonnet-5-5
…t combination of speed and intelligence. Five breaking changes affect code already running on Claude Sonnet 5: * [Turn off up-front thinking with `between_tools`](https://platform.claude.com/docs/en/…
overview
Claude Developer Platform · in the page
models/sonnet-5/overview
…| * **Context:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 20…
overview
Claude Developer Platform · in the page
release-notes/overview
…ude.com/en/articles/12138966-release-notes). For updates to Claude Code, see the [complete CHANGELOG.md](https://github.com/anthropics/claude-code/blob/main/CHANGELOG.md) in the `claude-code` repos…
claude-fable-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-fable-5
…nowledge cutoff may be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-fable-5-1
Claude Developer Platform · in the page
release-notes/system-prompts/claude-fable-5-1
…nowledge cutoff may be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-haiku-3-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-haiku-3-5
…ader 1") and leaves a blank line before and after headers, lists, and code blocks. For emphasis, Claude uses asterisks or underscores consistently (e.g., *italic* or **bold**). When creating lists, it…
claude-haiku-4-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-haiku-4-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-haiku-5-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-haiku-5-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-opus-4
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4
…odel string 'claude-opus-4-20250514'. Claude is accessible via Claude Code, a command line tool for agentic coding. Claude Code lets developers delegate coding tasks to Claude directly from their term…
claude-opus-4-1
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4-1
…el string 'claude-opus-4-1-20250805'. Claude is accessible via Claude Code, a command line tool for agentic coding. Claude Code lets developers delegate coding tasks to Claude directly from their term…
claude-opus-4-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4-5
…ude-haiku-4-5-20251001' respectively. Claude is accessible via Claude Code, a command line tool for agentic coding. Claude Code lets developers delegate coding tasks to Claude directly from their term…
claude-opus-4-6
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4-6
…ude-haiku-4-5-20251001' respectively. Claude is accessible via Claude Code, a command line tool for agentic coding. Claude Code lets developers delegate coding tasks to Claude directly from their term…
claude-opus-4-7
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4-7
…aiku-4-5-20251001' respectively. Claude is accessible through Claude Code, a tool for agentic coding that lets developers delegate coding tasks to Claude directly from the command line, desktop app,…
claude-opus-4-8
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-4-8
…ttps://anthropic.com/glasswing'. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-opus-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-opus-5-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-opus-5-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-sonnet-3-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-3-5
…in discussion on a wide variety of topics. Claude uses markdown for code. Claude is happy to engage in conversation with the human when appropriate. Claude engages in authentic conversation by resp…
claude-sonnet-3-7
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-3-7
…string 'claude-3-7-sonnet-20250219'. Claude is accessible via 'Claude Code', which is an agentic command line tool available in research preview. 'Claude Code' lets developers delegate coding tasks to…
claude-sonnet-4
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-4
…el string 'claude-sonnet-4-20250514'. Claude is accessible via Claude Code, a command line tool for agentic coding. Claude Code lets developers delegate coding tasks to Claude directly from their term…
claude-sonnet-4-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-4-5
…e-haiku-4-5-20251001' respectively.** Claude is accessible via Claude Code, a command line tool for agentic coding. **Claude Code lets developers delegate coding tasks to Claude directly from their te…
claude-sonnet-4-6
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-4-6
…biology, cybersecurity, and LLM R&D. Claude is accessible via Claude Code, a command-line and desktop tool for agentic coding, and Claude Cowork, a desktop tool for non-developers to automate file an…
claude-sonnet-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
claude-sonnet-5-5
Claude Developer Platform · in the page
release-notes/system-prompts/claude-sonnet-5-5
…ge cutoff may still be accurate. Claude is accessible through Claude Code, an agentic coding tool that lets developers delegate coding tasks to Claude from the command line, desktop app, or mobile ap…
overview
Claude Developer Platform · in the page
release-notes/system-prompts/overview
…em prompt also encourages certain behaviors, such as always providing code snippets in Markdown. This prompt is periodically updated to improve Claude's responses. These system prompt updates do not a…
develop-tests
Claude Developer Platform · in the page
test-and-evaluate/develop-tests
…ow for automated grading (for example, multiple-choice, string match, code-graded, LLM-graded). 3. **Prioritize volume over quality:** More questions with slightly lower signal automated grading is be…
handle-streaming-refusals
Claude Developer Platform · in the page
test-and-evaluate/strengthen-guardrails/handle-streaming-refusals
…'s how to detect and handle streaming refusals in your application: <CodeGroup exclude="shell:cURL, shell:CLI"> <CodeGroupItem language="cURL"> Detecting a refusal in the stream and resetting t…
mitigate-jailbreaks
Claude Developer Platform · in the page
test-and-evaluate/strengthen-guardrails/mitigate-jailbreaks
…the user instead of acting on it. ``` </Accordion> * **JSON-encode untrusted content.** Where possible, wrap third-party strings in a JSON object rather than concatenating them into free-form…
reduce-latency
Claude Developer Platform · in the page
test-and-evaluate/strengthen-guardrails/reduce-latency
…st and fastest level, and leaves room in `max_tokens` for thinking: <CodeGroup> ```bash cURL # For time-sensitive applications, use Claude Haiku 5.5 at low effort curl https://api.anthropic.com…
Escalate hard decisions with the advisor tool
Claude Code CLI · in the page
advisor
…ports it](#choose-an-advisor-model). After the session starts, Claude Code shows an `Advisor Tool (experimental) is on and may use more tokens · /advisor` notification. To stop using the advisor, see…
How the agent loop works
Claude Code CLI · in the page
agent-sdk/agent-loop
…ture that power your SDK agents. The Agent SDK lets you embed Claude Code's autonomous agent loop in your own applications. The SDK is a standalone package that gives you programmatic control over to…
Configure your agent
Claude Code CLI · in the page
agent-sdk/configuration
…r, project, and local settings. For more information, see [Use Claude Code features in the SDK](/docs/en/agent-sdk/claude-code-features.md). ## Choose a model Unless the `model` option, your setting…
Track cost and usage
Claude Code CLI · in the page
agent-sdk/cost-tracking
…age shows the estimated total\_cost\_usd.](https://mintcdn.com/claude-code/ikqp3_70mqIahteV/images/agent-sdk/message-usage-flow.svg?fit=max\&auto=format\&n=ikqp3_70mqIahteV\&q=85\&s=68497aee338e01cc74…
Give Claude custom tools
Claude Code CLI · in the page
agent-sdk/custom-tools
…nt-sdk/todo-tracking.md#model-availability) in `allowedTools`, Claude Code also opts the session in. | Option | Layer | Effect | | :- | :- | :- | | `tools: ["Read", "Grep"]` | Availability | Only the…
Examples
Claude Code CLI · in the page
agent-sdk/examples
…minimal TypeScript project to clone when you want to start from repo code ## Explore a demo application The applications in [`claude-agent-sdk-demos`](https://github.com/anthropics/claude-agent-sdk…
Rewind file changes with checkpointing
Claude Code CLI · in the page
agent-sdk/file-checkpointing
…r `rewind_files()` (Python). When you rewind to a checkpoint, Claude Code deletes the files it created and restores the files it modified to their content at that point. Claude Code skips a tracked p…
Intercept and control agent behavior with hooks
Claude Code CLI · in the page
agent-sdk/hooks
…ecution points with hooks Hooks are callback functions that run your code in response to agent events, like a tool being called, a session starting, or execution stopping. With hooks, you can: * **B…
Hosting the Agent SDK
Claude Code CLI · in the page
agent-sdk/hosting
…ision on this page follows from how the SDK runs the agent. When your code calls `query()`, the SDK spawns a separate `claude` CLI process and talks to it over stdio. That subprocess owns the shell, t…
Connect to external tools with MCP
Claude Code CLI · in the page
agent-sdk/mcp
…MCP configuration for the Agent SDK. To add MCP servers to the Claude Code CLI so they load in every project, see [MCP installation scopes](/docs/en/mcp.md#mcp-installation-scopes). ## Quickstart Th…
Migrate to Claude Agent SDK
Claude Code CLI · in the page
agent-sdk/migration-guide
# Migrate to Claude Agent SDK > Guide for migrating the Claude Code TypeScript and Python SDKs to the Claude Agent SDK ## Overview The Claude Code SDK has been renamed to the **Claude Agent SDK** a…
Modifying system prompts
Claude Code CLI · in the page
agent-sdk/modifying-system-prompts
# Modifying system prompts > Choose between the `claude_code` preset and a custom system prompt, and customize behavior with CLAUDE.md, output styles, append, or a fully custom prompt. System prompt…
Observability with OpenTelemetry
Claude Code CLI · in the page
agent-sdk/observability
…. ## How telemetry flows from the SDK The Agent SDK runs the Claude Code CLI as a child process and communicates with it over a local pipe. The CLI has OpenTelemetry instrumentation built in: it rec…
Agent SDK overview
Claude Code CLI · in the page
agent-sdk/overview
# Agent SDK overview > Build production AI agents with Claude Code as a library An agent is an application that completes a task by planning its own steps and calling tools that read files, run comm…