smithery.ai

agent-tool-builder

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

First seen Mar 18, 2026

Installation

$ npx skills add https://smithery.ai

Summary

  • 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

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More details

Agent compatibility

Declared targets from SKILL.md / docs. Unmarked agents are not listed — the skill may still install via the CLI.

Claude Code Not declared
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Gemini CLI Not declared
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Package contents

Files included with this skill beyond the listing page.

  • skill md SKILL.md 1,673 B
  • docs SUMMARY.md 526 B

History

  1. First seen on skills.sh
  2. First recorded snapshot · 16 installs

SKILL.md

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