mail_list_recent

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds meaningful context beyond annotations: requires Mail.Read permission, returns id/subject/sender/date/preview, and orders newest first. It does not contradict annotations, and the added details help set expectations for behavior.

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 two sentences, front-loaded with the core action, then usage guidance, an alternative, and a permission note. Every clause earns its place, with no wasted 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?

For a simple read-only list tool with two optional parameters and no output schema, the description covers purpose, usage context, return fields, ordering, permission, and the alternative tool. It is fully self-contained and enables correct invocation without additional context.

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 coverage is 100%, with both parameters described ('Number of days back to fetch' and 'Maximum emails to return'). The description only adds the phrasing 'last N days' which mirrors the schema, so it does not significantly enhance parameter understanding. Baseline 3 is appropriate.

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 'List the signed-in user's most recent emails from the last N days, newest first' with a specific verb and resource scope. It distinguishes itself from mail_search by noting that mail_search is for known keywords/senders, and from mail_list_flagged by focusing on recency rather than flags.

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?

It explicitly provides when to use: 'Use for what came in today or catching up after time away' and names the alternative: 'mail_search is the tool when specific keywords or a sender are known.' This directly answers the when-to-use vs alternatives question.

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