Agent Tool Builder

by davila78da17d671b6fNo license32K starsListed Oct 8, 2026Updated Oct 8, 2026Repository updated today

Tools are how AI agents interact with the world. A well-designed tool is the difference between an agent that works and one that hallucinates, fails silently, or costs 10x more tokens than necessary. This skill covers tool design from schema to error handling. JSON Schema best practices, description writing that actually helps the LLM, validation, and the emerging MCP standard that's becoming the lingua franca for AI tools. Key insight: Tool descriptions are more important than tool implementa

Instructions onlyAI & Agents
AI-generated overview

Guides the design of AI agent tools: JSON schemas, descriptions, validation, error handling and MCP conventions.

What it does
This skill provides guidance for designing tools that AI agents call, covering JSON Schema design, description writing for LLMs, input examples, validation and error handling. It also addresses the MCP standard for AI tools and lists anti-patterns such as vague descriptions, silent failures and too many tools. It is an instructions-only skill and produces design guidance rather than code or files.
When to use it
Use it when defining or reviewing a tool that an LLM agent will call, such as a function-calling interface or an MCP tool. It is also useful when an agent hallucinates, loops or fails silently because of unclear tool schemas or descriptions.
Requirements
No scripts or runtime dependencies; it is an instructions-only skill. It assumes familiarity with JSON Schema and agent tool-calling concepts.

Agent Tool Builder

You are an expert in the interface between LLMs and the outside world. You've seen tools that work beautifully and tools that cause agents to hallucinate, loop, or fail silently. The difference is almost always in the design, not the implementation.

Your core insight: The LLM never sees your code. It only sees the schema and description. A perfectly implemented tool with a vague description will fail. A simple tool with crystal-clear documentation will succeed.

You push for explicit error hand

Capabilities

  • agent-tools
  • function-calling
  • tool-schema-design
  • mcp-tools
  • tool-validation
  • tool-error-handling

Patterns

Tool Schema Design

Creating clear, unambiguous JSON Schema for tools

Tool with Input Examples

Using examples to guide LLM tool usage

Tool Error Handling

Returning errors that help the LLM recover

Anti-Patterns

❌ Vague Descriptions

❌ Silent Failures

❌ Too Many Tools

Related Skills

Works well with: multi-agent-orchestration, api-designer, llm-architect, backend

Source and attribution

Source:davila7/claude-code-templatesincli-tool/components/skills/ai-research/agent-tool-builderat commit8da17d6

License: No license

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