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

Annotations only provide destructiveHint=falsehol; the description adds useful context that the operation reuses the project's shared media library and returns a video_id for downstream use. However, it does not disclose other operational details such as auth requirements, default behavior, or failure modes, and annotations do not cover those.

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?

Two tight sentences with the primary action and distinguishing claim front-loaded. The second sentence adds return-value and next-step information without filler.

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 simple 3-param tool with no output schema, the description covers the essential invocation path: existing project, return artifact, and downstream instructions. It could mention defaults for optional parameters or side effects on the media library, but the core call is sufficiently complete.

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 0%, so the description must compensate for parameter meaning. It clarifies project_id's role as an existing project and mentions video_id, but name and aspect_ratio are left entirely to the schema with no additional semantic guidance.

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 'create', a clear object 'NEW video', and the scope 'inside an existing project'. The explicit note that no new project is needed distinguishes it from video_editor_create_project without requiring schema inspection.

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?

Makes the prerequisite explicit ('existing project') and instructs the caller to pass the resulting video_id to instruct/export, which provides downstream routing. It does not explicitly list when to prefer an alternative like create_project, so exclusions are implied rather than stated.

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