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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful behavioral context beyond that: it lists only files in a specific folder, orders them newest first, and discloses the return payload needed for later attachment.

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 compact sentence that front-loads the object and scope, then adds ordering, return fields, and practical purpose. Every part earns its place with no filler or redundancy.

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?

This is a simple, well-annotated, one-parameter tool with no output schema, and the description compensates by stating the return fields and ordering. It also names the source and prerequisite relationship to attachment, so an agent has enough context to invoke it correctly.

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?

There is only one parameter, account, and the schema already describes it as 'Account id from list_accounts', giving 100% schema coverage. The description adds little parameter-specific detail, but none is needed because the schema fully documents the source of the value.

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 states a specific verb and resource: listing uploaded files waiting in 'mailmcp-uploads' of an account. It also adds ordering and output-field details, which distinguishes it from related sibling tools like upload_attachment or get_attachment.

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 wording clearly implies when to use it: to retrieve files staged from upload_attachment or an upload link, and to obtain the {folder, uid, part} identifiers needed to attach them. It does not name alternative tools explicitly, but the context is clear and no exclusions are stated.

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