Get Attachment Metadata

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds the crucial behavioral fact that no file content is returned, which is exactly the ambiguity an agent would otherwise have for an 'attachment' tool.

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?

Two sentences, zero padding, with the purpose and the key caveat both front-loaded.

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?

An output schema exists so return values need no explanation, and only one required parameter exists. Complete for a simple read, though naming the sibling that fetches actual file content would close the last gap.

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 coverage is 100% and the attachment_id parameter is already documented with its pattern and origin in the upload endpoint. The description only restates that it is a temporary Sending attachment_id, adding little 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?

States a specific verb (inspect) and resource (temporary Sending attachment_id) and scopes it to pre-send validation. 'Metadata only, not file bytes' implicitly separates it from mailbox_get_attachment and mailbox_read_attachment, though those siblings are never named.

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?

'Before sending' gives a clear usage moment, but there is no explicit when-not guidance and no routing to alternatives such as read_attachment for actual bytes or the upload endpoints that produce the ID.

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