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

With no annotations provided, the description carries the full behavioral burden and does so well: it discloses the payment model ($0.65 deposit in Nano/XNO, settles at actual model cost + 20%, change returned, no account needed), an observed runtime (~2m 11s, last run $0.27), and that outputs are image + video saved to disk with file paths in the result. It stops short of describing failure modes or what happens if payment is abandoned.

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 pipeline and output information is front-loaded and dense, with each clause carrying real content (stages, outputs, pricing, runtime). It is slightly disorganized and contains a visibly truncated fragment ('Defaul…'), which costs a point.

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 zero-required-param, three-stage generative pipeline with no output schema and no annotations, the description supplies the essential return shape (image + video with file paths) plus pricing and runtime expectations. The two-phase _payment_id handshake is covered by the schema rather than the description, leaving only minor gaps.

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 World, Motion, and _payment_id are already fully documented, including the two-phase payment flow for _payment_id. The description's flow diagram ('text:World -> text:Motion') adds marginal pipeline-mapping meaning but no syntax or format detail beyond the schema, 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?

The description conveys that this tool generates a short film by chaining three models (Muse builds a miniature, Wan animates it, Mirelo adds foley), and the pipeline notation clarifies the stages. However, it is narrated through model names rather than stated as a crisp verb+resource, and it never distinguishes itself from siblings like photo-to-video or storyboard-relay.

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?

There is no explicit when-to-use guidance and no named alternatives among the sibling tools. The line 'Compare the silent and sounded takes' hints at a comparison use case but does not tell the agent when to pick this over photo-to-video or storyboard-relay.

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