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

Despite all annotations being false, the description discloses critical behavioral traits: the link expires in one hour, anyone with the link can PUT/POST a file, the file lands in 'mailmcp-uploads' and appears in list_uploads. It also clarifies that the tool itself does not upload; it only returns a link. This goes well beyond the annotations.

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 concise, two sentences, front-loading the core purpose, then providing actionable details on usage, expiry, and alternatives. Every sentence adds value with no filler.

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?

With no output schema, the description fully explains the return value (a link) and its behavior, including expiry, upload method, destination, and visibility in list_uploads. It also covers the decision between self-uploading vs. handing the link to the user. Nothing essential is missing.

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 single parameter 'account' is already described as 'Account id from list_accounts'. The description does not add additional parameter-specific detail, but given high coverage, a 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 clearly states the verb 'Returns' and the resource 'a one-hour HTTPS upload link for an account', and further explains what the link does. It distinguishes itself from siblings by explicitly mentioning 'files too big for upload_attachment' and referencing list_uploads for the result.

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 explicit usage guidance: use it for files on the user's disk or files too big for upload_attachment, and provides a conditional directive to upload yourself if you can run commands, otherwise give the link to the user. This clearly differentiates from alternatives.

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