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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the description needn't restate safety. It goes well beyond them by disclosing the 24-hour retention window, credential-level (not conversation-level) scoping, and the duplicate-on-reupload behavior — the kind of context an agent cannot infer from structured fields. The 'empty list does not mean nothing was uploaded' caveat is a genuinely useful false-negative warning.

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?

Front-loaded with the resource and returned fields, then the exclusions, then scoping — a logical order with no filler sentences. It is slightly longer than needed because 'scoped to the calling credential' and 'never lists another user's files' restate the same isolation guarantee.

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?

Output schema exists, so return-value shape is handled structurally, and the description still contextualizes the fields it mentions. Retention, scope, source-of-write, and the upload_media boundary together cover everything needed to call this correctly or decide against it.

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 no parameters, so parameter semantics are moot and the baseline of 4 applies. The description correctly spends no words re-explaining inputs and instead uses the space for scoping and retention semantics.

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?

States a specific verb and resource (list files uploaded through the file_manager widget) and enumerates the returned fields (cdn_url, name, size, content type), so the agent knows exactly what comes back. It also names the sibling it is distinct from (upload_media), removing ambiguity.

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?

Explicitly says it does not list media uploaded with upload_media and that a cdn_url returned by upload_media cannot be recovered here — a clear when-not-to-use rule tied to a named alternative. It also notes that re-uploading creates a duplicate rather than updating, which tells the agent not to expect dedup behavior.

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