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

Annotations already declare readOnlyHint=true, and the 'GET /files' note reinforces the read-only semantics. Beyond that the description adds the returned attribute set (size, type, purpose, validation status) but says nothing about auth requirements, pagination, or result limits, which is the sort of context that would raise this above the annotation baseline.

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?

Two tightly packed sentences, front-loaded with the resource scope and finishing with the returned fields plus the underlying endpoint. No filler and nothing buried.

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, describing the returned attributes (size, type, purpose, validation status) is genuinely useful compensation, and the read-only annotation covers safety. The only gap is the absence of any pagination or ordering note for a list operation.

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, so there is nothing for the description to disambiguate; the baseline of 4 applies. No parameter semantics are needed or missing.

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?

Specific verb+resource ('List uploaded data files') with the scope of file kinds (fine-tune, eval, batch-api inputs, job outputs) enumerated, and it lists the fields returned. This clearly distinguishes it from the other list_* siblings (batches, endpoints, models, fine-tunes), which an agent can rule out at a glance.

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 is only implied by the description of what is returned; there is no explicit when-to-use guidance, no exclusions, and no mention of the obvious alternative together_get_file for fetching a single file's details. Adequate for a simple zero-arg lister but leaves routing to inference.

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