search_messages

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

Beyond the readOnlyHint annotation, the description discloses important behavior: returned fields, newest-first ordering, server-side date/unread/flagged filtering, local header matching over max_scan candidates, truncation semantics, and the fact that message bodies are never searched. These details materially affect how an agent should invoke and interpret the 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 compact and front-loaded: purpose first, then return shape, filtering mechanics, truncation, and the body-search limitation. Every sentence adds useful information without redundancy.

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 13 parameters and no output schema, the description is largely complete: it states the return fields and explains the key filtering and truncation behavior. Minor details such as folder defaults and account handling are left to the schema, which is reasonable given the high schema coverage.

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?

Schema description coverage is high at 92%, so the schema already documents most parameters. The description still adds cross-parameter meaning by explaining which filters run server-side, which run locally over max_scan, and why truncated results may occur.

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 uses a specific verb and resource: "Search or list messages" and specifies newest-first ordering. It is clear what the tool does, but it does not explicitly distinguish itself from siblings such as read_message or list_folders.

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?

Usage is implied by "Search or list messages" and the note that bodies are never searched, but the description does not explicitly say when to use this tool versus alternatives like read_message or get_thread. The server-side versus local filtering distinction helps, but is not framed as usage guidance.

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