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

Annotations already flag mutation, non-idempotence and destructiveness, so the description's extra value is the async contract (returns jobId, poll get_job) and the credit-spend warning, both of which the agent needs before invoking. It does not cover failure/retry semantics or rate limits.

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?

Three dense sentences, no filler, operating constraints (async, credits, URL imports) front-loaded behind the core purpose. Every clause carries 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 correctly explains the async return and how to retrieve the result. Annotations cover the safety profile. The remaining gap is per-parameter guidance for the five undocumented fields.

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 only 13% (just firstFrame), and 8 parameters exist. The description adds real value for firstFrame/referenceImages (URLs, import first) and modelKey (list_studio_models), but leaves prompt limits, duration, resolution, aspectRatio, and generateAudio entirely to the schema's constraints.

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 (generate) and resource (single video clip) and scopes it to the Studio model catalog, which distinguishes it from the sibling seedance_generate_video and create_video tools. It does not explicitly name those siblings, so it stops short of a 5.

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 a usable workflow: call list_studio_models for keys, poll get_job until succeeded/failed, import URLs before passing firstFrame/referenceImages. It never states when to pick this over seedance_generate_video or create_video, so no explicit exclusions.

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