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

Annotations only declare non-read-only/non-idempotent/destructive; the description adds the traits that actually matter: the call is ASYNC and returns a jobId, the follow-up is get_job until succeeded/failed, and it SPENDS CREDITS. It further discloses that frame/reference fields require URLs that must be imported first. This is rich behavioral context beyond the structured fields, with no contradiction.

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 the core verb+scope, then layered: async contract, cost warning, then parameter-specific rules. Every clause is load-bearing and there is no redundant restatement of the schema.

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 supplies the return contract (jobId + polling via get_job) and covers the non-obvious input rules for reference/edit models. A note on auth/permission requirements or the meaning of generateAudio is the main omission, but an agent has enough to invoke and follow up 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 only 36%, so the description must carry meaning; it does so for the hard parameters by explaining that firstFrame/lastFrame/referenceImages/referenceVideos/referenceAudios take URLs and by defining the edit-model semantics of referenceVideos[0]. Self-evident params (prompt, resolution, aspectRatio) are left to the schema, which is acceptable, though duration ranges and modelKey sourcing could have been restated.

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+resource ('Generate a single video clip') scoped to 'the Studio model catalog', which cleanly separates it from siblings like seedance_generate_video and create_video. The parenthetical pointer to list_studio_models tells the agent exactly which catalog key space this tool consumes.

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 operational routing: fetch keys via list_studio_models and poll get_job after the call. It also states the rule for edit models (source clip goes in referenceVideos[0], never referenceImages). It stops short of explicitly naming when to prefer this over create_video or seedance_generate_video, but the context is clear enough to act on.

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