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

Annotations declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false; the description adds the meaningful behavioral detail that a tab is opened in the user's page, which is a visible side effect not captured by the annotations. It omits that repeated calls create duplicate compositions/tabs (relevant to idempotentHint=false) and says nothing about the token/session prerequisite.

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?

Four tight sentences that front-load what happens and then layer the essential `files` constraint and doc pointers. The final partsBoard sentence is the weakest link since it describes a prop absent from 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?

For a 9-parameter mutation tool with no output schema, the description never says what the call returns (e.g., a composition identifier the agent needs for later set_props/update_composition calls), and the undocumented boilerplate params (width/height/fps/durationInFrames) are left to name inference. The read_skill pointers partly offset this, but key lifecycle information is missing.

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?

With only 33% schema coverage across 9 parameters, the description does useful work by explaining `files` (path-to-source map that must include the entry) and restating the entry default. But fps, width, height, durationInFrames, and name get no semantic elaboration, and the 'partsBoard prop' it mentions does not exist anywhere in the schema, which actively muddies the parameter picture.

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?

Specific verb ('Creates') plus resource ('a new composition from TSX source') plus the non-obvious side effect that it opens the result as a tab in the user's Motion page. That side effect alone distinguishes it from update_composition, get_composition, and close_composition in the sibling list.

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?

Explicitly routes the agent to read_skill with two topic names (motion for API specifics, motion-craft for design), which is actionable guidance before calling. It does not, however, state when to prefer update_composition over creating a new one or what prerequisites (e.g., an active session from connect) are required.

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