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

With no annotations, the description carries the full burden and does disclose real behavior: worker dispatch to Modal, variable credits by model/file size, file deletion after processing, and audit links. It omits the critical operational fact that there are zero input parameters, and its 'choose length, framing and audio' claim conflicts with the empty schema.

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 opening sentence is well front-loaded, but the bulk is marketing/pricing filler ('no per-workspace subscription,' 'one-time credit pack,' pricing links) that consumes space without helping the agent invoke the tool.

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?

Business/credit context is thorough, but for a zero-parameter, unannotated, no-output-schema tool the description fails to explain how to actually invoke it or what providing a 'scene' entails, leaving a key gap.

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?

The schema has zero parameters (baseline 4). But the description asserts the agent can 'choose the length, framing and audio,' implying configurable inputs that do not exist, which misleads rather than clarifies parameter semantics.

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 first sentence gives a specific verb+resource: 'Describe a scene and turn it into a short video.' That distinguishes it from image, music, and enhancement siblings. However it says 'choose the length, framing and audio' with no parameters, leaving how it's invoked unclear.

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 or comparison to alternatives among the many mio_ai_* siblings. The remaining text is pricing/credit policy rather than usage direction, so the agent must infer when to pick this over tools like talking_head or video_enhancer.

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