mailbox_stats

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

Annotations include readOnlyHint: true, which indicates the tool is safe and read-only. The description adds that it shows 'volume, unread counts and top senders', which conveys what data is returned but does not disclose details like whether it aggregates across all accounts or only the default account, or whether 'recent period' is defined by the 'days' parameter. Since annotations cover the safety profile, a 3 is appropriate.

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 sentence, concise and front-loaded. It directly states what the tool does without unnecessary words, making it easily scannable by an AI agent.

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 tool has an output schema (not shown here), which likely explains return values. The description is somewhat complete given it's a stats tool, but it lacks explicit guidance on usage context, such as how to use the 'days' parameter or what 'volume' means. With two parameters and no schema descriptions, the description does not provide enough details to fully understand the tool's behavior, though the output schema might help.

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 0%, so the description must compensate. It mentions 'recent period' which likely corresponds to the 'days' parameter, and it implies account-specific stats which ties to the 'account' parameter. However, it does not explain the meaning or format of those parameters beyond what the names and defaults suggest. The description only partially compensates for the lack of schema descriptions, so a 3 is reasonable.

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 'Show volume, unread counts and top senders for the recent period' clearly states the tool's purpose: it provides a summary of mailbox statistics, including volume, unread counts, and top senders. It is distinguishable from siblings like search_mail or get_message as it is about aggregated stats, not individual 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?

The description does not specify when to use this tool versus alternatives, nor does it mention any prerequisites or exclusions. It implies usage for summarizing mailbox activity, but no guidance is provided about when to prefer it over other tools like search_mail or get_thread. There is no mention of which account or time period it applies to beyond the parameters.

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