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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent write on a closed world, so the baseline bar is lower. The description adds genuinely non-obvious behavior beyond those hints: the linked partner clip is split as well, which materially affects the result and cannot be inferred from the annotations.

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?

Three short sentences, no filler: what it does and the linked-partner side effect come first, the fps convention second, the get_timeline prerequisite last. Each sentence carries distinct information.

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 mutation tool with no output schema, the description covers unit semantics, side effects, and the prerequisite lookup, which is most of what an agent needs. It does not say what the call returns (e.g., ids of the two new clips), which is a meaningful gap for a tool that creates new clips the agent may need to reference.

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 coverage is 100%, so the baseline is 3. The description earns above baseline by clarifying that atFrame is interpreted in the target timeline's fps, which is unit information the schema does not state and which prevents an off-by-rate error.

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 (blades/splits) plus resource (clips) plus the exact mechanism (at a timeline frame), which clearly distinguishes it from trim_clips, move_clips, and remove_clips. An agent can pick this out of the sibling list without opening the schema.

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 tells the agent to call get_timeline first to obtain clip ids, which is a concrete prerequisite chain. It stops short of stating when not to use it (e.g., versus trim_clips for shortening a clip), so it's strong context but not full routing guidance.

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