# 7 Rules for Designing Tool Definitions That AI Agents Can Reliably Use

DevFeed: [7 Rules for Designing Tool Definitions That AI Agents Can Reliably Use](<https://devfeed.tech/articles/your-agent-isn-t-dumb-your-tools-are-18104.md>)

Original publisher: [Read original article](<https://thetshaped.dev/p/7-rules-tool-definitions-ai-agents-tool-design-software-design-architecture>)

Author: The T-Shaped Dev

Published: 2026-09-08T12:19:46Z

Content type: tutorial

Language: en

Sources: [The T-Shaped Dev](<https://devfeed.tech/sources/the-t-shaped-dev.md>)

Topics: [Code](<https://devfeed.tech/topics/code.md>), [Tool](<https://devfeed.tech/topics/tool.md>), [API](<https://devfeed.tech/topics/api.md>), [Vibe coding](<https://devfeed.tech/topics/vibe-coding.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [code](<https://devfeed.tech/tags/code.md>), [coding](<https://devfeed.tech/tags/coding.md>), [coding-agents](<https://devfeed.tech/tags/coding-agents.md>), [developer](<https://devfeed.tech/tags/developer.md>), [tool](<https://devfeed.tech/tags/tool.md>), [tools](<https://devfeed.tech/tags/tools.md>)

## AI overview

A tutorial on designing tool definitions for AI agents. It explains that models rely on a tool's name, description, and schema, so ambiguous contracts can cause incorrect behavior. The article recommends focused tools, descriptions that guide selection and state when not to use a tool, and structured decisions followed by deterministic code.

## Source excerpt

7 rules for tool definitions a model can't misread, starting with the sentence that fixes the most bugs. (8 min)