Lesson 629 of 1596
Tool-Calling Prompt Design: Function Calling and Disambiguation
When models call tools, the tool description is the contract. Sloppy descriptions mean the model picks the wrong tool, calls it incorrectly, or doesn't call it when it should. Here's how to write descriptions that get reliable invocation.
Creators · Prompting · ~24 min read
The premise
Tool descriptions are the contract between your app and the model; sloppy descriptions produce unreliable behavior at scale.
What AI does well here
- Write tool descriptions in second-person ('Use this when', 'Do not use this for')
- Specify both positive and negative use cases ('Use for X. Do NOT use for Y.')
- Document parameter constraints in the schema and reinforce them in the description
- Test tool selection against scenarios designed to be ambiguous
What AI cannot do
- Make every tool selection deterministic (some ambiguity always exists)
- Replace error handling for malformed tool calls
- Substitute for user-facing confirmation on consequential actions
Key terms in this lesson
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