mail_search

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

Beyond annotations, the description discloses the return structure ('Returns id, subject, sender, date and a preview snippet'), ordering ('newest first'), folder constraints, and permission requirement ('Requires Mail.Read'). This adds substantial behavioral context without contradicting the readOnly, idempotent annotations.

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 three sentences, front-loaded with the core purpose, and every sentence adds value: purpose, return/ordering, alternatives, and permissions. There is no redundancy or fluff.

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?

The description thoroughly covers the tool's behavior—search scope, output fields, ordering, folder options, permission requirements, and sibling tool alternatives—despite lacking an output schema. It provides enough context for an agent to select and invoke the tool correctly.

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 input schema already covers all parameters with clear descriptions, so the baseline is 3. The description does reinforce query semantics and folder enumeration but adds little beyond the schema's own parameter documentation.

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: 'Search the signed-in user's mailbox by keyword, subject or sender name.' It specifies the resource (mailbox), the action (search), and the fields searched, and it distinguishes itself from sibling tools by naming alternatives.

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 explicit usage guidance: 'Use mail_list_recent when the ask is time-based rather than keyword-based, and mail_get_thread to read a whole conversation.' It also explains the scope of searchable folders, giving clear context for when to use this tool.

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