contacts

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the read-only hint, the description adds valuable context regarding the search mechanism ('exact part first, then close matches'). This explains the operational behavior of the query parameter that is not covered by simple typing.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is very concise, using two powerful sentences to convey the search logic, the matching behavior, and the default action for a null query. Zero waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that the annotations cover safety (read-only) and the description covers usage modes and search logic, the definition is complete enough for an agent to reliably select and invoke the tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Although schema coverage is 100%, the description significantly clarifies the semantics of the 'query' parameter by explaining the two distinct modes of operation: searching by name/address, or listing the most written-to contacts when the query is empty.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: finding people you email by name or address. It also implicitly distinguishes this search function from a singular contact management tool (like a potential sibling named 'contact').

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly details a critical usage scenario: 'Without a query, lists the people you write to most.' This provides clear direction to the agent on how to use the tool when the primary search parameter is omitted.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.