Definition
Plain language
A short spec of what a piece of code expects to receive and what it hands back.
As stated in the literature
The declared input and output types of a function or tool interface; in agent frameworks, tools and pseudo-tools are exposed with a name and type signature that the model uses to decide how to call them.
Also called: type signatures
Why it matters: It matters because it tells a model exactly how to call a tool correctly, so the pieces fit together without guesswork.
For example, a weather tool's type signature might say it takes a city name as text and returns a temperature as a number.
Heard on the show
“I'm calling them tools because to the agent they look exactly like tools — they have a name, a type signature, a description.”Episode 110 — How an Agent Got 44 Points Better by Mining Its Own Scratch Paper