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

With no annotations provided, the description carries the full transparency burden. It discloses the URL's validity period ('valid until the file is hard-deleted'), future auth re-check in Phase 6, and access control ('gated behind FILES_SURFACE_ENABLED + per-user allowlist'). This goes beyond the schema, though it omits error behaviors and the full response shape.

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 three sentences, front-loaded with the core purpose, and includes necessary detail on URL behavior and gating without unnecessary padding. The phase-specific specifics are slightly dense but acceptable.

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 covers what the tool does, common use cases, URL expiry, and access control. It lacks a detailed list of returned metadata fields and error handling, but for a simple read tool with no output schema, it is sufficiently informative.

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 input schema already provides thorough descriptions for both parameters (slug formats and file_id derivation), so the tool description adds minimal parameter-level value. Baseline 3 is appropriate given schema coverage is 100%.

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 clearly states 'Fetch metadata + a download URL for a single file by id', providing a specific verb, resource, and scope. It distinguishes itself from siblings like list_files (listing) and get_doc (documents) by focusing on single-file metadata and download URL.

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 gives explicit use cases: 'useful for an agent reading file contents server-side' or 'surfacing a download link in a reply'. It also mentions the gating requirement. However, it does not explicitly state when not to use it or name alternative tools.

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