files.describe

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

No annotations are present, so description must disclose behavior. It states no token cost, local operation, no auth/rate limits, and lists the metadata fields it returns. This covers safety and scope. Missing error handling or return format, but for a read-only metadata fetch this is acceptable.

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 packs multiple pieces of information (no token cost, field list, local operation, use case, param requirement) in a compact paragraph. It leads with the core value proposition and avoids redundant filler. Each sentence contributes.

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?

The description lists the key metadata fields returned, so an agent can infer what 'everything' includes. It also clarifies the non-content nature. Without an output schema, this is sufficient for a simple metadata tool. The usage note makes it clear when to use 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?

Schema covers the single 'id' parameter fully with a description. The description adds that 'id' must be a valid integer, reinforcing the type but not adding new meaning beyond the schema. With 100% schema coverage, baseline is 3; description adds marginal value.

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 ('Return everything about a file') and resource, and explicitly contrasts with files.read by noting it does not pull content. Names the relevant sibling alternatives in usage, making it clear what it is not (a content reader).

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 states when to use: when you'd otherwise chain multiple read/list calls just to decide whether to read the file. This provides a clear decision rule and implies not to use it for getting content. Also notes it operates locally with no auth/rate limits, which affects suitability.

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