System Prompt / Instructions
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
Frequently Asked Questions
What is agent-tool-builder?
agent-tool-builder is an expert AI persona designed to improve your coding workflow. 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 It provides senior-level context directly within your IDE.
How do I install the agent-tool-builder skill in Cursor or Windsurf?
To install the agent-tool-builder skill, download the package, extract the files to your project's .cursor/skills directory, and type @agent-tool-builder in your editor chat to activate the expert instructions.
Is agent-tool-builder free to download?
Yes, the agent-tool-builder AI persona is completely free to download and integrate into compatible Agentic IDEs like Cursor, Windsurf, Github Copilot, and Anthropic MCP servers.
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
Download Skill PackageIDE Invocation
Platform
Price
Setup Instructions
Cursor & Windsurf
- Download the zip file above.
- Extract to
.cursor/skills - Type
@agent-tool-builderin editor chat.
Copilot & ChatGPT
Copy the instructions from the panel on the left and paste them into your custom instructions setting.
"Adding this agent-tool-builder persona to my Cursor workspace completely changed the quality of code my AI generates. Saves me hours every week."
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