List Mailbox Inbox Messages

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

Annotations already indicate read-only and non-destructive behavior. The description adds valuable context about the data being untrusted and that only summaries are returned, which is beyond the 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 two sentences, front-loaded with purpose and key distinctions, efficient and without superfluous information.

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?

The description covers basic purpose and a warning, but lacks details on pagination via cursor, filter combinations, and output structure. However, existence of an output schema partially compensates. Adequate but with noticeable gaps.

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 only 10% (only 'id' described). The description lists filter types (cursor, date, folder, keyword, search) but does not explain their semantics, behavior, or interactions, leaving a significant gap for a tool with 10 parameters.

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 it lists message summaries for a mailbox with various filters, and explicitly distinguishes the sibling tool shipmail_get_mailbox_inbox_message for full body retrieval.

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 clear context on when to use this tool (listing summaries) and points to the get tool for full body. It warns about untrusted data but does not explicitly exclude other alternatives for specific use cases like threading.

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