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

Beyond the readOnly/idempotent annotations, the description discloses important non-obvious behavior: an empty result is not an error, files sit in a draft in their own Drafts folder, and the draft is deleted automatically once files are attached or swept later. It also warns the agent not to offer deletion, which is exactly the kind of behavioral context annotations cannot 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?

The description is dense but every sentence earns its place: purpose and return value, call timing, empty-result handling, and deletion behavior. Important warnings are front-loaded enough to be noticed, and the final explanatory sentence justifies the DO NOT instruction rather than padding it.

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 tool with one parameter, no output schema, and no nested objects, the description is complete. It explains what the tool returns (`fileRef` per file), how to respond to an empty result, and the lifecycle of the underlying draft. There is no critical missing context.

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 `uploadId` parameter is already documented as 'The `uploadId` from create_upload_link.' The description reinforces this by referencing `create_upload_link`, but it does not add new parameter-level meaning beyond the schema. A baseline of 3 is therefore 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 uses a specific verb-resource pairing: 'Look for the files an upload link put into this mailbox' and states the concrete return value, a `fileRef` for each file. It clearly distinguishes this from sibling check tools by anchoring it to upload links and the `create_upload_link` flow.

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?

The description is explicit about when to call it: 'Call this after create_upload_link - either straight after uploading the file yourself, or once the person says they have.' It also gives a clear when-not: if nothing has arrived, do not call repeatedly; tell the person what you are waiting for.

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