setClipRange

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

Annotations only declare readOnly=false, destructive=false, openWorld=false; the description goes well beyond by disclosing mutation semantics ("Only the fields you pass are changed"), timeline side effects ("All clips are re-laid back-to-back afterwards, so downstream clips shift automatically"), and a subtle result condition ("joinedIntoNeighbour when an edit made them so"). These are exactly the consequences an agent can't infer 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?

Front-loaded with purpose, then the when/when-not rule, then parameter and return nuances. It is dense and em-dash-heavy but each clause carries distinct information (trim distinction, crop semantics, re-layout behavior, join condition). Slightly packed rather than wasteful.

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 5-parameter mutation with no output schema and modest schema coverage, the description covers the essential effects: partial update, automatic re-layout, crop reversal, and the join result. It does not cover error/permission behavior or interactions when range and crop are combined in one call, but nothing critical for correct invocation 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 coverage is only 40%, so the description must compensate, and it does for the two undocumented numeric fields by framing them as in/out points in source-time seconds. cropRegion gets more meaning than the schema gives, including the "null shows the whole frame" reversal behavior and its availability via getCurrentDocument. clipId is left implicit, which is minor but a small gap.

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+resource: "Set a clip's in/out points (source-time seconds) to shorten its head or tail ... and/or its crop." It immediately distinguishes itself from the sibling trim operations by defining a trim as cutting "a span inside the clip." An agent can separate this from setTrim/addTrim/addTrims without opening a 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 explicit gating ("Change the range ONLY when the user explicitly asks to shorten or extend a clip") plus a named anti-pattern with a redirect: "Do NOT use this for 'remove silences' or 'cut pauses' — for those, use addTrim." This is exactly the when/when-not/alternative structure needed to route correctly.

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