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

Annotations already declare a non-read-only, non-destructive, non-idempotent, closed-world operation, so the bar is lower; the description still adds substantive context beyond them: the link is private, valid for 60 minutes, sends nothing, and requires the user's account. These are auth, lifecycle, and side-effect details the annotations do not convey.

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?

Three compact sentences, front-loaded with the trigger condition and followed by the lifecycle and handoff. No filler; every clause carries decision-relevant information.

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 covers the return artifacts (URL to give the user, upload_id for create_letter), validity window, side effects, and auth requirement. An agent has everything needed to call it and act on the result.

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 tool takes zero parameters and schema coverage is 100%, so there is nothing for the description to disambiguate; baseline is 4. It usefully explains what the caller supplies downstream (upload_id to create_letter) even though no input is required.

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?

It names a specific verb and resource ('Creates a private upload page') and precisely scopes it: a PDF resident on the user's own device that cannot be passed as URL or base64. This cleanly distinguishes it from sibling tools like upload_document and create_letter.

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?

Explicit trigger ('when the user wants to post a PDF that is on their own device and cannot be passed as a URL or base64') plus the downstream handoff ('pass upload_id to create_letter'). The agent knows both when to call it and what to do with the result.

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