mail

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

Annotations already mark it read-only and non-destructive, and the description still adds meaningfully: it requires Automation access for Mail, bodies are never fetched, results are capped at 25 with a `truncated` flag signaling more may exist. It also discloses the inbox-only scan scope, which is a behavioral limit not visible in any structured field.

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?

Front-loaded with the action, then a compact "Pointers:" list mapping field names to meanings, then scope/limit and a sibling recommendation. Every clause carries information, though the pointer enumeration makes it denser than strictly necessary for a one-parameter 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 one-parameter search tool it covers everything an agent needs: matching semantics, inbox-only scope, output field meanings, the truncation cap, the auth prerequisite, and the routing decision to `mail_search`. An output schema exists, yet the description still clarifies the one field (`truncated`) whose meaning matters operationally.

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 single `query` parameter has 0% schema description coverage, so the description must carry it — and it does, explaining that matching is a subject OR sender substring. It does not specify case sensitivity, whitespace handling, or whether multiple terms are ANDed, which keeps it below a 5.

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?

States a specific verb and resource ("Search the Mail inbox") and narrows the matching semantics to subject OR sender substring. It also explicitly separates itself from `mail_search`, which reaches every mailbox, so an agent can pick between the two without opening schemas.

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?

Gives an explicit preference rule: "Prefer `mail_search`, which reaches every mailbox and reports the account," which is precisely the condition that selects the sibling over this tool. It also tells the caller to forward the returned `folder` value straight to `mail_body`, closing the follow-up loop.

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