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

Beyond annotations, the description discloses key behavior: it returns a job object, the download URL expires after 15 minutes, and job_status_url should be polled if the job is still running after about 100 seconds. It also states failure conditions for private/login-only content and refused music content, which is valuable operational context.

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 front-loaded and efficient for a tool with job polling, media-kind variants, and licensing restrictions. Some sentences repeat schema details, such as the kind-to-format mapping, but the overall structure is clear and most content earns its place.

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?

Given the tool's complexity and the absence of an output schema, the description is complete enough: it explains the job response shape, polling behavior, URL expiry, media-kind options, and all major restrictions. An agent has what it needs to call the tool and handle its result 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 description coverage is 100%, so the schema already documents all six parameters, including enum meanings and timestamp formats. The description reinforces the kind mapping and adds contextual constraints like the 12-hour video limit, but it does not add much parameter meaning beyond what the schema already provides.

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 states a specific verb and resource: 'Create a temporary download of a public post.' It also distinguishes the tool from its sibling by naming transcribe_video for spoken text, so an agent can tell what this tool is for 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?

It gives explicit usage guidance: which kind value to use for each media type, when to use transcribe_video instead, the 12-hour video limit, and the permission/licensing constraints. It also explicitly says music is refused and warns not to work around the error.

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