Claude Tool Calling Patterns
Comprehensive guide for AI agents on proper Claude-style tool calling with correct syntax, patterns, and examples
npx skills add majiayu000/claude-skill-registry --skill claude-tool-calling --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Claude Tool Calling Patterns ## Overview This skill provides comprehensive guidance on proper Claude-style tool calling syntax for AI agents building systems that interact with Claude's API. Claude uses a unique XML-based tool calling format that differs from other LLM APIs. **Key Insight**: Claude's tool calling uses XML-style function_calls blocks with nested invoke and parameter tags. Understanding this structure is critical for building reliable agent systems. ## When to Use This Skill - **Building AI agent systems** that need to call tools via Claude API - **Implementing function calling** in Claude-powered applications - **Debugging tool calling issues** in existing Claude integrations - **Training other AI agents** to properly format tool calls - **Migrating from OpenAI function calling** to Claude tool use ## Prerequisites - **Claude API access**: Anthropic API key - **XML/HTML familiarity**: Understanding of tag structure - **JSON knowledge**: Tool parameters use JSON format - **Programming basics**: Calling APIs from your language of choice ## Skill Usage Type **EDUCATIONAL** - Study the patterns and examples, implement in your Claude API integration. The examples are r
- Overview
- When to Use This Skill
- Prerequisites
- Skill Usage Type
- Core Concepts
- Tool Calling Structure
- Key Differences from OpenAI
- Critical Rules
- Rule 1: Always Use functioncalls Block
- Rule 2: One invoke Per Tool
- Rule 3: Individual parameter Tags
- Rule 4: JSON for Complex Types
- Rule 5: Parallel Tool Calls
- Rule 6: Sequential Tool Calls
What does the Claude Tool Calling Patterns skill do?
Comprehensive guide for AI agents on proper Claude-style tool calling with correct syntax, patterns, and examples
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill claude-tool-calling --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.