Mmcp.market

claude-api skill

by anthropics·anthropics/skills·179k stars

Reference for the Claude API / Anthropic SDK — model ids, pricing, params, streaming, tool use, MCP, agents, caching, token counting, model migration. TRIGGER — read BEFORE opening the target file; don't skip because it "looks like a one-liner" — whenever: the prompt names Claude/Anthropic in any form (Claude, Anthropic, Fable, Opus, Sonnet, Haiku, `anthropic`, `@anthropic-ai`, `claude-*`, `us.anthropic.*`, `[1m]`); the user asks about an LLM (pricing/model choice/limits/caching) — never answer from memory; OR the task is LLM-shaped with provider unstated (agent/MCP/tool-definition/multi-agent/RAG/LLM-judge/computer-use; generate/summarize/extract/classify/rewrite/converse over NL; debugging refusals/cutoffs/streaming/tool-calls/tokens). SKIP only when another provider is being worked on (overrides all triggers): OpenAI/GPT/Gemini/Llama/Mistral/Cohere/Ollama named in the query; OR `grep -rE 'openai|langchain_openai|google.generativeai|genai|mistralai|cohere|ollama'` over the project hits (run this grep FIRST if no provider named — don't Read the file).

A97/100content scan

Is the claude-api skill safe?

Clean: nothing in its files matched our rules. We read 69 files in the folder on 2026-09-28.

  • lowSKILL.md:1

    The description is over 1,024 characters, the limit agents read.

    1068 characters

Install the claude-api skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description. 

git clone --depth 1 https://github.com/anthropics/skills.git /tmp/skills
mkdir -p ~/.claude/skills
cp -r /tmp/skills/skills/claude-api ~/.claude/skills/claude-api
available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

Building LLM-Powered Applications with Claude

This skill helps you build LLM-powered applications with Claude. Choose the right surface based on your needs, detect the project language, then read the relevant language-specific documentation.

Before You Start

Scan the target file (or, if no target file, the prompt and project) for non-Anthropic provider markers - import openai, from openai, langchainopenai, OpenAI(, gpt-4, gpt-5, file names like agent-openai.py or -generic.py, or any explicit instruction to keep the code provider-neutral. If you find any, stop and tell the user that this skill produces Claude/Anthropic SDK code; ask whether they want to switch the file to Claude or want a non-Claude implementation. Do not edit a non-Anthropic file with Anthropic SDK calls. (Exception: the prompt-audit subcommand is non-interactive and does not stop here - it records non-Anthropic provider markers in its report's stated assumptions and never proposes switching a non-Anthropic file to the Anthropic SDK.)

Output Requirement

When the user asks you to add, modify, or implement a Claude feature, your code must call Claude through one of:

  1. The official Anthropic SDK for the project's language (anthropic, @anthropic-ai/sdk, com.anthropic.*, etc.). This is the default whenever a supported SDK exists for the project.
  2. Raw HTTP (curl, requests, fetch, httpx, etc.) - only when the user explicitly asks for cURL/REST/raw HTTP, the project is a shell/cURL project, or the language has no official SDK.

Never mix the two - don't reach for requests/fetch in a Python or TypeScript project just because it feels lighter. Never fall back to OpenAI-compatible shims.

Never guess SDK usage. Function names, class names, namespaces, method signatures, and import paths must come from explicit documentation - either the {lang}/ files in this skill or the official SDK repositories or documentation links listed in shared/live-sources.md. If the binding you need is not explicitly documented in the skill files, WebFetch the relevant SDK repo from shared/live-sources.md before writing code. Do not infer Ruby/Java/Go/PHP/C# APIs from cURL shapes or from another language's SDK.

If WebFetch or repository access fails (network restricted, timeouts, clone blocked): do not keep retrying - write code from the patterns and namespace/package tables in the {lang}/ file, run the compiler or interpreter on it, and iterate on the error output. For statically-typed SDKs (C#, Java, Go) a compile-fix loop against local errors reaches working code faster than blocked network research.

Defaults

Unless the user requests otherwise:

For the Claude model version, please use Claude Opus 5, which you can access via the exact model string claude-opus-5. Please default to using adaptive thinking (thinking: {type: "adaptive"}) for anything remotely complicated. And finally, please default to streaming for any request that may involve long input, long output, or high maxtokens - it prevents hitting request timeouts. Use the SDK's .getfinal_message() / .finalMessage() helper to get the complete response if you don't need to handle individual stream events

Warning: API Drift - Your Training Prior May Be Stale

Several common Claude API shapes changed in 2025-2026. If you recall a pattern from training, verify it against the {lang}/ files in this skill before writing - the rows below are the most frequent drift points:

The {lang}/ files in this skill are authoritative over recalled patterns.

Subcommands

If the User Request at the bottom of this prompt is a bare subcommand string (no prose), search every Subcommands table in this document - including any in sections appended below - and follow the matching Action column directly. This lets users invoke specific flows via /claude-api . If no table in the document matches, treat the request as normal prose.

Language Detection

Before reading code examples, determine which language the user is working in (exception: for the prompt-audit subcommand, skip this section's ask steps - the audit is non-interactive and its inventory is language-agnostic; when no language is inferable, proceed without asking and state the assumption in the report):

  1. Look at project files to infer the language:
  • .py, requirements.txt, pyproject.toml, setup.py, Pipfile -> Python** - read from python/
  • .ts, .tsx, package.json, tsconfig.json -> TypeScript - read from typescript/
  • .js, .jsx (no .ts files present) -> TypeScript - JS uses the same SDK, read from typescript/
  • .java, pom.xml, build.gradle -> Java** - read from java/
  • .kt, .kts, build.gradle.kts -> Java - Kotlin uses the Java SDK, read from java/
  • .scala, build.sbt -> Java** - Scala uses the Java SDK, read from java/
  • .go, go.mod -> Go** - read from go/
  • .rb, Gemfile -> Ruby** - read from ruby/
  • .cs, .csproj -> C# - read from csharp/
  • .php, composer.json -> PHP** - read from php/
  1. If multiple languages detected (e.g., both Python and TypeScript files):
  • Check which language the user's current file or question relates to
  • If still ambiguous, ask: "I detected both Python and TypeScript files. Which language are you using for the Claude API integration?"
  1. If language can't be inferred (empty project, no source files, or unsupported language):
  • Use AskUserQuestion with options: Python, TypeScript, Java, Go, Ruby, cURL/raw HTTP, C#, PHP
  • If AskUserQuestion is unavailable, default to Python examples and note: "Showing Python examples. Let me know if you need a different language."
  1. If unsupported language detected (Rust, Swift, C++, Elixir, etc.):
  • Suggest cURL/raw HTTP examples from curl/ and note that community SDKs may exist
  • Offer to show Python or TypeScript examples as reference implementations
  1. If user needs cURL/raw HTTP examples, read from curl/.

Language-Specific Feature Support

Every SDK language above supports both the beta Tool Runner and Managed Agents (beta) - Python (@betatool decorator), TypeScript (betaZodTool + Zod), Java (annotated classes), Go (BetaToolRunner in the toolrunner pkg), Ruby (BaseTool + toolrunner), C# (BetaToolRunner + raw JSON schema), PHP (BetaRunnableTool + toolRunner()); code entry points are in the Tool Use Patterns quick reference below. cURL is raw HTTP (no SDK features) and supports Managed Agents.

Managed Agents code examples: see the reading guide in the ## Managed Agents (Beta) section below.

Which Surface Should I Use?

Start simple. Default to the simplest tier that meets your needs. Single API calls and workflows handle most use cases - only reach for agents when the task genuinely requires open-ended, model-driven exploration. "Simplest" means the least code you own: for a hosted, scheduled, or memory-backed agent, Managed Agents is usually the simplest option (no loop code, no state files, no scheduler), even though it's a bigger platform.

Note: Managed Agents is the right choice when you want Anthropic to run the agent loop and host the container where tools execute - file ops, bash, code execution all run in the per-session workspace. If you want to host the compute yourself or run your own custom tool runtime, Claude API + tool use is the right choice - use the tool runner for the agentic loop - its per-turn hooks still give you approval gates, logging, error interception, and conditional execution (see shared/tool-use-concepts.md) - or the manual loop when you want to own the entire loop yourself.

Cloud-provider access. Claude Platform on AWS is Anthropic-operated with same-day API parity - see shared/claude-platform-on-aws.md for client setup. For per-feature availability on Claude Platform on AWS, Amazon Bedrock, Google Vertex AI, and Microsoft Foundry, see shared/platform-availability.md - that table is the single source of truth in this skill; do not infer availability from anywhere else.

Building an Agent: Four Approaches

Once you've decided you actually need an agent (open-ended, model-driven tool use), there are four distinct ways to build one. Two independent questions separate them: who supplies the harness (the agent loop + context management) and who supplies the deployment (the infra the agent runs on). The Tool Runner and the Claude Agent SDK both supply a harness only - you still host and deploy them yourself - which is why they're easy to conflate. Managed Agents (CMA) is the only option that supplies both the harness and managed deployment; the manual loop supplies neither.

The harness/deployment split is the key mental model: options 1, 2, and 4 all leave deployment to you; only option 3 (CMA) adds managed deployment. Options 1-3 are what this skill generates; option 4 is a different library with its own docs - see the disambiguation below.

Tool Runner != Claude Agent SDK. These sound alike but are different packages:

- Tool Runner is part of the regular Anthropic API SDK (anthropic / @anthropic-ai/sdk), reached via client.beta.messages.toolrunner. It automates the request -> execute -> loop cycle for tools you define*. No built-in tools, no filesystem access, no sandbox - you supply every tool and host the compute. It is option 2 above, a thin helper over POST /v1/messages.

- Claude Agent SDK (claude-agent-sdk / @anthropic-ai/claude-agent-sdk) is Claude Code packaged as a library. It ships built-in tools (file read/write/edit, bash, grep, web search), the full agent loop, context management, hooks, subagents, permissions, and sessions. You call query(prompt, options) and it drives everything.

Both are harness-only - you host and deploy them. The difference is scope of harness: the Tool Runner loops over tools you define (with per-turn hooks for approval, interception, result modification, and retries - but no built-in tools); the Agent SDK is the full Claude Code harness with built-in tools. Neither provides managed deployment - that's what Managed Agents (CMA) adds (Anthropic hosts the loop and a per-session sandbox).

This skill covers the Claude API and Managed Agents (options 1-3); it does not generate Claude Agent SDK code. If the user actually wants the Claude Agent SDK, point them to its docs (code.claude.com/docs/en/agent-sdk) - don't substitute the API Tool Runner for it, or vice-versa.

Should I Build an Agent?

Before choosing the agent tier, check all four criteria:

  • Complexity - Is the task multi-step and hard to fully specify in advance? (e.g., "turn this design doc into a PR" vs. "extract the title from this PDF")
  • Value - Does the outcome justify higher cost and latency?
  • Viability - Is Claude capable at this task type?
  • Cost of error - Can errors be caught and recovered from? (tests, review, rollback)

If the answer is "no" to any of these, stay at a simpler tier (single call or workflow).

Architecture

Everything goes through POST /v1/messages. Tools and output constraints are fea

More skills from anthropics/skills

  • Aacademy-guideStop and check this skill before finishing any reply to a question about how to use Claude or a Claude product — it recommends matching courses, tutorials, and use cases from Claude Academy (academy.claude.com), Anthropic's learning hub. Trigger on: "how do I", "how can I", "getting started with", "what can Claude do", "teach me", "learn to use"; questions about artifacts, projects, skills, plugins, connectors, MCP; requests about rolling Claude out to a team, class, or organization; and any ask for training materials, onboarding content, or learning resources. Use it when the user is learning how to use a feature or product — not when they are mid-task and just want the task done. This skill composes with other skills: after consulting product documentation to answer how a Claude feature works, also check here for a matching course or tutorial — a docs-grounded answer and an Academy recommendation belong together. Only recommend on a strong match; never invent Academy content.
  • Aalgorithmic-artCreating algorithmic art using p5.js with seeded randomness and interactive parameter exploration. Use this when users request creating art using code, generative art, algorithmic art, flow fields, or particle systems. Create original algorithmic art rather than copying existing artists' work to avoid copyright violations.
  • Abrand-guidelinesApplies Anthropic's official brand colors and typography to any sort of artifact that may benefit from having Anthropic's look-and-feel. Use it when brand colors or style guidelines, visual formatting, or company design standards apply.
  • Acanvas-designCreate beautiful visual art in .png and .pdf documents using design philosophy. You should use this skill when the user asks to create a poster, piece of art, design, or other static piece. Create original visual designs, never copying existing artists' work to avoid copyright violations.
  • Adiscernment-nudgeAfter you give a substantive answer or draft that the user may act on — advice or recommendations, drafted artifacts such as goals, plans, pitches, proposals, or emails, estimates or projections, analysis or interpretation of data, factual claims they may rely on, or a multi-step argument — invoke this skill BEFORE finalizing your reply and then, if it applies, append 2-3 short follow-up questions, each tied to something specific in what you just produced, that help the user check key facts, probe the reasoning or assumptions, and notice missing context. Do this at most once per conversation. Skip it when the user asked a trivial how-to or simple lookup, wants a purely educational explanation, asked you only to format, convert, or assemble a file from content they provided, is writing code they will run, is doing creative writing or casual chat, or already asked you to double-check, cite, or review — the skill file explains these boundaries and the exact output format.
  • Adoc-coauthoringGuide users through a structured workflow for co-authoring documentation. Use when user wants to write documentation, proposals, technical specs, decision docs, or similar structured content. This workflow helps users efficiently transfer context, refine content through iteration, and verify the doc works for readers. Trigger when user mentions writing docs, creating proposals, drafting specs, or similar documentation tasks.
  • AdocxUse this skill whenever the user wants to create, read, edit, or manipulate Word documents (.docx files) or Word templates (.dotx files). Triggers include: any mention of 'Word doc', 'word document', '.docx', '.dotx', or requests to produce professional documents with formatting like tables of contents, headings, page numbers, or letterheads. Also use when extracting or reorganizing content from .docx or .dotx files, inserting or replacing images in documents, performing find-and-replace in Word files, working with tracked changes or comments, or converting content into a polished Word document. If the user asks for a 'report', 'memo', 'letter', 'template', or similar deliverable as a Word or .docx file, use this skill. Do NOT use for PDFs, spreadsheets, Google Docs, or general coding tasks unrelated to document generation.
  • Afrontend-designGuidance for distinctive, intentional visual design when building new UI or reshaping an existing one. Helps with aesthetic direction, typography, and making choices that don't read as templated defaults.
  • Ainternal-commsA set of resources to help me write all kinds of internal communications, using the formats that my company likes to use. Claude should use this skill whenever asked to write some sort of internal communications (status reports, leadership updates, 3P updates, company newsletters, FAQs, incident reports, project updates, etc.).
  • Amcp-builderGuide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).
  • ApdfUse this skill whenever the user wants to do anything with PDF files. This includes reading or extracting text/tables from PDFs, combining or merging multiple PDFs into one, splitting PDFs apart, rotating pages, adding watermarks, creating new PDFs, filling PDF forms, encrypting/decrypting PDFs, extracting images, and OCR on scanned PDFs to make them searchable. If the user mentions a .pdf file or asks to produce one, use this skill.
  • ApptxUse this skill any time a .pptx or .potx file is involved in any way — as input, output, or both. This includes: creating slide decks, pitch decks, or presentations; reading, parsing, or extracting text from any .pptx or .potx file (even if the extracted content will be used elsewhere, like in an email or summary); editing, modifying, or updating existing presentations; combining or splitting slide files; working with templates (.potx), layouts, speaker notes, or comments. Trigger whenever the user mentions \"deck,\" \"slides,\" \"presentation,\" or references a .pptx or .potx filename, regardless of what they plan to do with the content afterward. If a .pptx or .potx file needs to be opened, created, or touched, use this skill.

All agent skills → · MCP servers