Get Attachment Metadata

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

Beyond the annotations, the description discloses the key behavioral trait that the download_url is short-lived and may require a repeat call after expiry. It does not cover auth requirements or rate limits, but it adds meaningful operational context that an annotation alone would not convey.

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 tightly written sentences with the prerequisite front-loaded and the critical expiry behavior immediately after. Every phrase earns its place and there is no redundant restatement of the title.

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 simple three-parameter read tool with full schema coverage, rich annotations, and an output schema, the description covers the essential invocation context and the non-obvious ephemeral URL behavior. An agent has enough information to call it correctly and handle expiry.

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%, so the input schema already documents mailbox_id, message_id, and attachment_id. The description confirms that the result pertains to 'that exact attachment' but does not add semantics beyond the schema.

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 action and result: it returns attachment metadata plus a fresh short-lived download_url for the exact attachment. That clearly distinguishes it from general message retrieval, though it does not explicitly name or distinguish sibling content-reading tools such as mailbox_read_attachment or mailbox_get_attachment_text.

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 gives clear usage context: use it after finding a message attachment, fetch the returned URL promptly, and call the tool again if the URL expires. It does not explicitly state when not to use it or compare it against the attachment-content siblings, so it stops short of full alternative routing.

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