list_emails

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

Given no annotations, the description discloses useful behavior: messages are returned newest-first with index 1 as the most recent, and summaries include a message_ref. This adds meaningful context about ordering and integration, though it does not mention read-only status or rate limits.

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 primary action, then return value details, then ordering. Every sentence adds value without redundancy, making it appropriately concise and well-structured.

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 listing tool with no output schema, the description explains the return format (summaries with message_ref), pagination, and ordering. It does not cover error handling or rate limits, but for the simplicity of the operation, it is sufficiently complete.

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 schema covers 100% of parameters with descriptions, so the baseline is 3. The description's mention of newest-first ordering reinforces the offset semantics already present in the schema, but it does not add new parameter-specific information beyond what the schema provides.

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 emails in a specific mailbox with pagination', which is a specific verb+resource with scope. It distinguishes itself from siblings like get_email (single email retrieval) and search_emails (searching) by focusing on listing a mailbox.

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 provides clear context by describing pagination and the return of message_ref for use with other tools like get_email, reply_email, move_email, etc., implying it is the entry point for email workflows. However, it does not explicitly state when to prefer this over search_emails, so it lacks exclusions.

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