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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, and the description adds substantial behavior beyond them: the two-state status machine, the 6-hour media_url validity window, its renewal when the post goes out, and that the URL serves as both video_url and photo_url. This is exactly the runtime context an agent cannot get from annotations.

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?

One front-loaded sentence with the status semantics first and the return payload second; the nested parenthetical is dense but every clause (validity window, renewal, dual URL use) carries real information.

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, the description must carry the return contract and does: status values, media_url with lifetime, kind, size, and content type. Nothing needed to interpret the response is missing.

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 single parameter is already documented as 'The upload_id returned with the upload link.' The description's 'by upload_id' adds no syntax, format, or sourcing detail beyond what the schema states, so the baseline 3 applies.

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 (returns status) and resource (a file uploaded through a PostWire upload link) keyed by upload_id, which clearly distinguishes it from sibling create_upload_link. An agent can tell it apart without opening any 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?

Implies the polling workflow by describing the waiting→done transition and tying the tool to an upload link, so an agent knows to call it after creating a link. It does not explicitly name create_upload_link as the prerequisite or state when-not to use it, so it stops short of full routing guidance.

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