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

The annotations already declare readOnlyHint and idempotentHint, and the description is consistent with those (searching is non-mutating and idempotent). However, the description adds no extra behavioral context beyond the annotations—no mention of scope limits, authentication implications, or result ordering—so it neither enhances nor contradicts the given hints.

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 a single, tight sentence that leads with the action verb and states the core behavior immediately. There is no redundant wording, filler, or unnecessary detail—ideal conciseness for a simple search tool.

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?

For a simple search tool with no output schema, the description is reasonably complete: it names the resource, the action, and the expected return ('matching messages'). Minor gaps exist (e.g., no mention of result ordering, matching criteria beyond parameters, or whether results include full message bodies), but these are non-critical for basic invocation.

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 100% (tag, limit, query, offset each have descriptions), so the baseline is 3. The tool description itself adds no additional parameter meaning beyond the schema; the parameter descriptions are present but terse (e.g., 'What to look for' for query is vague), though not misleading.

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 ('Search'), states the resource ('the account's mail'), and describes the outcome ('return matching messages'). It is clear and differentiated from read/inbox tools by the 'search' framing, but it does not explicitly name a sibling tool it is not, so it falls short of a 5.

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 no guidance on when to use this tool versus related mail siblings like mail_inbox, mail_read, or mail_info. It does not clarify whether this is for full-text search vs. listing the inbox or fetching a specific message, leaving the selection decision to the agent's inference.

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