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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds only per-request cost information (useful but peripheral) and says nothing about response behavior, size limits, or auth scope beyond what annotations provide.

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?

It is short and front-loads the tool name, but the bulk of the body is pricing markup rather than functional content, and the pricing block arguably belongs in metadata rather than the description. There is no wasted prose, but also almost no substance.

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 not be explained, but for a tool surrounded by near-identical attachment getters the description provides no disambiguation of which attachment source it targets. Missing scope/routing detail leaves the agent unable to place it confidently among siblings.

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 both draft_id and attachment_id are documented in the schema itself; per the rubric this yields a baseline of 3. The description contributes no additional parameter meaning (e.g., ID formats or where draft_id comes from).

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 is only the header 'Get Attachment' plus pricing boilerplate, which essentially restates the tool name/title. It does not specify what kind of attachment is fetched (draft vs message vs thread) or what the returned payload is, so an agent cannot distinguish it from the many sibling attachment getters.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as get_agentmail_inbox_draft_attachment or get_agentmail_thread_attachment. The only added text is pricing, which does not help an agent decide when this tool applies.

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