list_emails

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals important behaviors: newest-first ordering, merging of all enabled accounts when account is omitted, per-account limit handling, unread_only filtering, and ISO date lower bound for 'since'. This goes beyond a minimal description, though it does not cover edge cases like pagination or error handling.

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 highly concise and well-structured: a one-sentence purpose followed by a parameter list. Each line is informative and necessary, with no redundant filler. The front-loaded purpose makes the tool's intent immediately clear.

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 list tool with an existing output schema, the description covers key behavioral aspects: sorting order, account scoping, and filtering semantics. It also explains the merging behavior, which is crucial for understanding results. Minor gaps include a precise definition of 'recent' and explicit handling of pagination, but the output schema and limit parameter mitigate this.

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 zero descriptions (0% coverage), so the description fully compensates by explaining every parameter: account key source and merging behavior, since as ISO date lower bound, unread_only as unseen messages, and limit as max rows per account when merging. This adds significant meaning beyond the raw schema types and defaults.

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: 'List recent emails, newest first.' The verb 'list' and resource 'emails' are specific, and the sorting order adds clarity. It is distinct from sibling tools like search_emails (which implies filtering/search) and get_email (which implies fetching a single email).

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 usage context through parameter explanations, including referencing list_accounts for the account key. However, it does not explicitly state when to use this tool over search_emails or get_email, nor does it mention exclusions. The usage guidance is implied rather than explicitly stated.

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