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

Annotations supply only readOnlyHint=false, so the description carries most of the burden and does it well: it discloses id retention on the left half, that the right half is new and is returned, the 100ms minimum-footage guard, and that transitions stay on the outer edges with a hard cut at the new seam. These are non-obvious side effects an agent could not derive from the 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?

Four short sentences, each carrying distinct information (operand, id behavior, guard condition, transition behavior), with the core action front-loaded. There is no filler or restatement of the tool name.

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 three-parameter mutation tool with no output schema and minimal annotations, the description covers the operand, the timing argument's coordinate system, the failure condition, and the identity of the returned value. Nothing an agent needs to invoke it correctly 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?

Schema description coverage is 100%, and the schema already spells out that at_ms is a timeline position rather than an element offset and that target_id accepts a scene or clip id. The description restates the timeline-millisecond framing but adds no new syntax or format detail beyond the schema, so 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?

States a specific verb and resource — cutting a scene or timeline clip in two at a timeline millisecond — and immediately distinguishes the two operand types. An agent knows exactly what operation is performed and on what entities without consulting 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?

Gives a clear applicability constraint: both halves must retain at least 100ms or the split refuses, which tells the agent when the call is valid. It does not, however, name or contrast with adjacent edit siblings such as studio.cut_range, studio.trim_clip, or studio.roll_edit, so the agent must infer which edit primitive to pick.

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