search-contacts

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

With no annotations, the description carries the full burden. It reveals that the tool queries Contacts.app, searches by name, and returns names and email addresses. It does not detail matching behavior (e.g., exact vs. fuzzy) or result limits, but the information is sufficient for a simple lookup tool.

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 three sentences, front-loaded with the key use case. Every sentence adds value with no redundancy. It is concise and well-structured.

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 the tool has only one parameter and an output schema (which likely details return structure), the description covers what is needed: when to use, what it does, and what it returns. It is complete for an agent to decide and invoke correctly.

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?

The schema provides only a string with minLength for the parameter 'query', but the description adds that it is a name to look up. This adds meaning beyond the bare schema. No further format details are given, which is adequate for a simple name search.

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 verb (looking up) and resource (person in Contacts.app by name) and specifies the goal (find email addresses before composing mail). It distinguishes from the sibling 'search-messages' by explicitly stating this queries Contacts, not the mailbox.

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?

The description provides explicit 'Use when' and 'Do not use when' guidance, including a named alternative ('search-messages'). This helps the agent select the correct tool in context.

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