get-mail-stats

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

Discloses behavioral traits: mentions that for the all-accounts path it provides per-account breakdown, and that using the account parameter triggers fast IMAP STATUS if IMAP-configured. Does not explicitly state it is read-only, but the context implies no side effects. Annotations are absent, so description carries the burden; this is good but could be marginally better.

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 extremely concise: two short sentences followed by a clear 'Do not use' directive. Structured with 'Use when', 'Returns', and 'Do not use when' for quick scanning. No extraneous words.

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 the tool has one parameter, an output schema (so return details are covered), and siblings are listed, the description fully covers when to use, what it returns, and key behavioral context. No missing information apparent.

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 has 100% coverage for the single optional parameter 'account'. The description adds value beyond the schema by explaining the all-accounts path behavior and the IMAP STATUS optimization, though it does not explicitly restate the parameter's optionality.

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 provides aggregate mailbox statistics including total/unread counts and recent-activity counts. It specifies the verb 'aggregate' and resource 'mailbox statistics', and distinguishes from sibling tools like get-unread-count and list-messages.

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?

Explicitly states when to use ('Use when: you want aggregate mailbox statistics') and when not to use ('Do not use when: you only need a single unread number...'), providing alternative tool names (get-unread-count, list-messages, search-messages).

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