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Agent Tool Builder

Design reliable tools (schemas, descriptions, validation, error handling, MCP) for AI agents

Source Download skill
Repository
sickn33/agentic-awesome-skills
Stars
49,023
Licence
MIT
Files
2 files

What it does

When installed, the agent gets guidance for designing the tools that AI models call to act on the world, such as functions for looking up data or running actions. It covers writing JSON schemas, descriptions that help the model choose the right tool, input validation, error handling, and the MCP (Model Context Protocol) standard. The skill also includes a Python example using Anthropic's SDK with mock tools, and warns that safety and authorization must be enforced in code, not just in descriptions.

Great for

  • Developers building function calling or tool use into an AI agent
  • Teams writing MCP servers and need consistent tool schemas
  • Engineers debugging agents that pick wrong tools or fail silently

Skip it if

  • Non-developers looking for a finished tool or app; this is design guidance, not a ready-made integration
  • Production systems that let agents trigger real external effects without separate approval and authorization controls, since the skill itself does not enforce them

Try asking

  • “Design a JSON schema and description for a tool that searches our product catalog”
  • “Review my MCP server tool definitions and suggest better error handling”
  • “Why does my agent keep calling the wrong tool? Improve the descriptions”
  • “Write validation and safe failure responses for a tool that updates customer records”
Step-by-step guide: how to use Agent Tool BuilderInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 2 original files, the MIT licence and an attribution note.

    agent-tool-builder.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip agent-tool-builder.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip agent-tool-builder.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Treat the example as a sketch: the weather and search tools return mock data, and you should pin and verify the SDK beta API before any billed call
  • Enforce authorization, bounded execution and approval inside your tool implementations, since descriptions only guide selection
  • Load only the sections of references/detailed-guide.md you need, and test tools with real inputs and failure cases

What's inside

  • references/detailed-guide.md
  • SKILL.md

Redistributed unmodified from sickn33/agentic-awesome-skills under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.