Designing Simple Tool Interfaces › What Makes a Good Tool Interface?

Before we dive into implementation details, let's think about what makes a tool easy for an agent to use. A good tool interface has three essential characteristics:

Clear purpose: The agent needs to understand what the tool does. Is it for calculations? Weather lookups? Database queries? The more specific and focused a tool is, the easier it is for the agent to decide when to use it.

Simple inputs: The tool should require only the information the agent can reasonably extract from a user's question. If you ask "What's the weather in Tokyo?", the agent should be able to extract "Tokyo" as the location parameter. If the tool requires complex nested data structures or obscure parameters, the agent will struggle to use it correctly.

Predictable outputs: The tool should return information in a format the agent can understand and incorporate into its response. A weather tool that returns {"temp": 72, "conditions": "sunny"} is easier to work with than one that returns a binary blob or a complex nested structure.

Think of it like designing an API for another developer. You want clear documentation, sensible parameters, and predictable responses. The same principles apply when designing tools for agents.