download_attachment

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

With no annotations, the description carries the full burden and discloses important behavior: overwrite refusal unless overwrite=true, rejection of paths outside the download directory, and the security-sensitive return of a sender-chosen filename under an "untrusted" key with a warning not to follow instructions found in it. It could still say more about permissions or error behavior, but the core mutation and safety traits are well covered.

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 compact, front-loaded with the core action, and each sentence adds distinct value: destination, overwrite behavior, path validation, and an important security warning. There is no redundant wording.

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 download tool with no output schema and no annotations, the description covers the essential action, overwrite behavior, path restrictions, and the shape of the returned saved path under the "untrusted" key. It is nearly complete, though it does not explain how to obtain attachmentId or whether authentication is required.

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 25%, so the description should compensate more for undocumented parameters. It explains the effect of overwrite and the path restriction, but messageId and attachmentId receive no semantic explanation beyond their names, leaving a meaningful gap for a low-coverage 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 uses a specific verb and resource: "Download an attachment into the configured download directory." It clearly distinguishes this action from sibling tools like list_attachments or get_message by describing a save-to-disk operation.

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?

Usage is implied by the tool name and description, but there is no explicit guidance on when to choose this tool versus list_attachments or get_message, nor any note that attachment IDs likely come from list_attachments. The overwrite and path constraints are useful behavioral rules but do not constitute when-to-use routing.

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