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

The description goes far beyond the sparse annotations: it discloses that files land in Drafts as a holding draft, that the draft cleans itself up when files are attached, that the link requires no sign-in or password, and that check_upload provides fileRef values. This gives the agent important side-effect awareness that nothing in the annotations or schema conveys.

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 long, but every sentence earns its place: purpose, side effects, two usage modes, the mandatory follow-up, and explicit anti-usage cases. It is front-loaded with the core purpose and clearly organized, so the length is justified by the amount of behavior it must convey without an output schema.

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?

Given zero parameters, no output schema, and minimal annotations, the description is remarkably complete. It covers what the tool returns indirectly (uploadUrl), what the user receives (a no-login link), what happens to files (draft + auto-cleanup), the follow-up call (check_upload), and the exclusion cases. An agent has enough context to decide when and how to invoke it correctly.

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?

The input schema has zero properties, so there are no parameter semantics to explain. The description still references the expected returned uploadUrl and filename convention for the curl path, which is useful, but that is output/invocation context rather than input-parameter meaning. A 4 matches the baseline for a zero-parameter tool.

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 opens with a specific verb and resource: "Produce a one-off link that puts files into this mailbox." It also distinguishes itself from siblings by explicitly saying when not to use it (files already in the mailbox via read_email, or files with a URL). This makes the tool's purpose unmistakable and distinct from related tools like check_upload and read_email.

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 guidance is exceptionally concrete: use it for files not in the mailbox and not reachable by URL, typically local files. It gives two explicit modes of use — direct curl upload versus giving the link to the person — and tells the agent to call check_upload afterwards. It also states clear exclusions: do not use for in-mailbox files or already-URL-reachable files.

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