upload_reference_media

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

The description goes well beyond the annotations: seven-day cleanup of public links, no credit spend but a positive purchased-credit prerequisite, and the API-key vs remote-OAuth auth distinction. It also states the return values (mediaUrl, measured duration). It stops short of describing failure modes for unsupported codecs or size limits, so not a 5.

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?

Six short sentences, front-loaded with purpose and then constraints, with no filler. It is dense to the point of being terse in places (credit prerequisite and auth path are compressed), but nothing is wasted.

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?

For a write operation with an output schema, the agent gets purpose, media constraints, credit requirement, link lifetime, and auth path — everything needed to call it correctly and interpret the result. Return values are already covered by the output schema and are still summarized.

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 0%, so the description must carry the load, and it does partially: sourceUrl is constrained to 'external direct HTTPS' links, the MP4/MOV vs WAV/MP3 split implicitly defines the kind enum, and modelId/tier are sourced from list_models. It leaves tier's role and the 40-char bound unexplained, so it does not fully compensate.

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?

Specific verb+resource: prepares an external direct HTTPS media reference for generate_video, and names the accepted formats. It explicitly ties itself into the workflow by naming siblings generate_video and list_models, so an agent can distinguish it from image/background/poster siblings without opening a 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?

Gives explicit routing rules: use list_models to pick modelId/tier, reuse on retries rather than permanent hosting, and — critically — 'Local files can be passed directly to generate_video,' which tells the agent when NOT to use this tool. This is a genuine when/when-not pair with named alternatives.

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