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Claude API Development Reference

Official

An authoritative reference skill that keeps Claude API code correct — model IDs, pricing, streaming, tool use, MCP, agents, caching, token counting and migrations, per language.

Dev & CodingIntermediate★ 177,818⑂ 21,068AI score 9/10Last updated: Sep 22, 2026

What it does

  • Fires automatically when a prompt mentions Claude/Anthropic/Opus/Sonnet/Haiku, or when the task is LLM-shaped (summarize, classify, extract, agent, MCP, RAG) with no provider named.
  • Detects the project language (Python, TypeScript, Java/Kotlin, Go, Ruby, C#, PHP, cURL) and restricts examples to that language's bundled docs.
  • Supplies a current model table with IDs, context windows and input/output pricing, and blocks invented date-suffixed model IDs.
  • Flags "API drift" where training memory is stale: thinking: {type: "adaptive"} vs budget_tokens, new web search/fetch tool versions, Files/Skills namespaces out of beta.
  • Gives decision tables for single call vs workflow vs manual loop vs Tool Runner vs Managed Agents vs the separate Claude Agent SDK.
  • Ships subcommands: migrate, prompt-audit, upgrade, cost-optimize, each executing a bundled step-by-step guide.

Who it's for

  • Backend and full-stack engineers shipping Claude API integrations.
  • Teams migrating older Claude code to newer models without breaking requests.
  • Architects deciding whether to host the agent loop themselves or use Managed Agents.
  • Operators trying to cut token spend without losing output quality.

Example uses

  1. "Add Claude-powered summarization to this Python service" → the skill detects Python, uses the official anthropic SDK with streaming and the recommended model ID.
  2. /claude-api migrate → confirms scope and target model, classifies each file, then applies breaking changes in order and audits prompts afterwards.
  3. /claude-api cost-optimize → builds a token profile, then ranks savings levers from free wins (caching, prompt hygiene) to tradeoffs (effort, model choice).

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/anthropics/skills/HEAD/skills/claude-api/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the skills/claude-api folder from the GitHub repo anthropics/skills into my ~/.claude/skills/claude-api/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone --depth 1 https://github.com/anthropics/skills.git /tmp/anthropic-skills && mkdir -p ~/.claude/skills && cp -r /tmp/anthropic-skills/skills/claude-api ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal.
  2. Clone the skills repo: git clone --depth 1 https://github.com/anthropics/skills.git /tmp/anthropic-skills
  3. Create the skills directory: mkdir -p ~/.claude/skills
  4. Copy this skill: cp -r /tmp/anthropic-skills/skills/claude-api ~/.claude/skills/
  5. Verify ~/.claude/skills/claude-api/ contains SKILL.md plus its subfolders (python/, typescript/, shared/, etc.) — the skill depends on those reference files.
  6. Restart Claude Code, then test with a request like "write Claude API code to summarize a file" or run /claude-api migrate.
View source on GitHub ↗