List messages

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

Annotations already declare readOnlyHint=true, and the description adds useful behavioral details: stable ordering across pages, headers-only returns, and a latency caveat for large mailboxes. It discloses why bodies are excluded without contradicting annotations.

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 five sentences, each adding value: purpose, ordering, return format, reasoning for headers-only, alternative, and performance caveat. It is front-loaded and free of fluff.

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?

Given the schema covers parameters, annotations cover safety, and no output schema is needed, the description fully covers return format, ordering, pagination, performance, and alternatives. It is complete for a listing tool.

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 100%, with each parameter already well-documented. The description adds context about ordering stability across pages, which relates to limit/offset, but does not significantly redefine parameters. 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 the tool lists mailbox messages newest first, returns headers only, and distinguishes itself from get_message (for bodies) and list_folders. It is specific about the resource and scope.

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 says to use get_message with an id to read a message body, and notes this tool never returns bodies. It also mentions performance behavior for large mailboxes, giving clear when-to-use context and an alternative.

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