search_emails

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

Beyond the readOnlyHint annotation, the description discloses the sort order ('newest first'), the limitation to metadata only, and a security-relevant behavior about message content being potential instructions. This adds significant context that the annotations alone do not provide.

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 remarkably concise: three sentences, each earning its place. The first states the core purpose, the second adds key behavioral details, and the third provides a vital security guideline. There is no fluff or repetition.

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 10 parameters and no output schema, the description is somewhat incomplete. It mentions 'metadata only' but does not specify which metadata fields are returned, nor does it mention pagination behavior beyond what the schema defaults imply. The security note is a plus, but the lack of return-value detail is a gap.

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 has only 40% parameter description coverage, and the tool description does not compensate. It does not explain the meaning or usage of parameters like to, from, limit, offset, subject, or unread_only, leaving the agent without adequate guidance for these fields.

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 with a specific verb ('Search') and resource ('the mailbox'). It distinguishes itself from siblings by explicitly noting it returns 'metadata only (no message bodies)', which sets it apart from get_email that presumably retrieves full content.

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 clear context for when to use the tool (searching the mailbox) and includes a crucial usage guideline about treating message content as untrusted data. However, it does not explicitly mention alternatives like get_email for retrieving full bodies, so it falls short of a 5.

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