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

Annotations already declare a safe, idempotent read, but the description adds substantive context the agent could not infer: retention windows (14 days on Free/Pro, expiry permanent), that a video returns the original upload, that images are kept indefinitely, and that download links are tokenless and expire after one hour. That is exactly the kind of operational detail annotations cannot carry.

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 purpose and parameter rules before the detail, and every sentence carries real information. It is dense and parenthetical-heavy, though, and the trailing list of return fields reads as a run-on; slight restructuring would improve scanability without losing content.

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?

No output schema exists, so the description must document return values, and it enumerates all of them (asset_id, version_id, url, version_url, kind, filename, size, download_url, available_until) including null semantics for images. Combined with retention, expiry, and permission guidance, an agent has everything needed to call and interpret this tool correctly.

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 schema already explains version-id-vs-asset-id, but the description adds the meaningful constraint that folder IDs are rejected and clarifies the polymorphic behavior of the single parameter. Good value beyond the schema, though for a one-parameter tool it is close to what a well-written schema field already conveys.

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 ('Get a download link for a version's file') and immediately frames the intent ('to work on it locally'). It also distinguishes itself from version_notes_get for live code versions, so an agent can pick it out of a large sibling list without opening the schema.

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 what ID to pass, that a folder id is refused, that view access is required, and routes to version_notes_get for a live version's source zip. It also gives fallback guidance (call again after an hour, hand download_url to the user when no shell is available), leaving little to inference.

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