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

Annotations contain only a title, so the description carries the burden of behavioral disclosure. It explicitly says 'Read-only' and 'connect in Account first,' covering both safety and authentication requirements; retention window and header-only behavior are visible in the schema, though not in the main description.

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 main description is two short sentences that front-load the action and then state the key constraints, with no filler. It appropriately defers detailed parameter behavior to the schema.

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?

Together with the schema, the definition covers the auth prerequisite, read-only behavior, pagination, limit, query syntax, retention limit, and the follow-up GmailRead tool. It only lacks an explicit differentiation from mail_search, and the absence of an output schema is partially mitigated by saying results are headers only.

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?

All three parameters have full descriptions in the input schema, so the high-coverage baseline applies and the main description adds no parameter-level detail. The rich query-parameter guidance is part of the schema itself rather than incremental to it.

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 names a specific action ('Search') and a specific resource ('the caller's connected Gmail'), which makes the tool's purpose immediately clear. It does not explicitly contrast itself with the sibling mail_search tool, leaving a small amount of ambiguity despite the clear scope.

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 tells the agent this is a read-only search and that an account must be connected first, which is useful prerequisite context. The query parameter's description also routes body retrieval to GmailRead, but it does not explicitly say when to prefer this tool over mail_search or mail_inbox.

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