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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear without description help. The description does add the published request price, which annotations do not cover, but it says nothing about authentication, rate limits, or response behavior.

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 short and front-loads the only substantive phrase, "Get Attachment." However, it is under-specified for a tool with this many siblings, and the embedded pricing boilerplate is not central to invoking the tool correctly.

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 schema is fully documented, an output schema exists, and annotations cover the read-only/idempotent behavior. Still, the description itself does not clarify the inbox-message scope or distinguish this attachment getter from sibling attachment tools, leaving context to be inferred from the tool name.

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%, and the three required parameters (inbox_id, message_id, attachment_id) are each described in the schema. The description adds no parameter meaning beyond what the schema already provides, so the baseline of 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 is essentially "Get Attachment," which restates the title "Inboxes - Get Attachment" rather than stating a distinct purpose. It does not differentiate this inbox-message attachment getter from sibling tools such as get_agentmail_draft_attachment, get_agentmail_inbox_draft_attachment, or get_agentmail_inbox_thread_attachment.

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?

No guidance is given about when to use this tool versus the many adjacent attachment and message retrieval tools. The only extra text is a pricing note, which does not help an agent choose between alternatives.

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