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

Annotations already disclose that this is a mutating, non-read-only, idempotent, non-destructive edit. The description adds important behavioral context not covered there: the edit changes source exposure while preserving the clip's timeline position and size, which is central to understanding the operation.

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?

The description is two sentences, front-loads the core effect, and contains no redundant or filler language. The reference to server instructions for return details is compact and appropriately defers rather than bloating the definition.

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?

With rich annotations, an output schema, and mostly described parameters, the description supplies enough core semantics to call the tool correctly. It does not explain the new timeline handle behavior, but that is already stated in the timeline_id schema description and output schema context.

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 75%, so most parameters are already documented in the schema, including the sign convention for by_frames and the preview enum. The description reinforces the earlier/later source direction but does not add meaningful semantics for clip_id, timeline_id, or the preview parameter beyond what the schema provides.

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?

The description states a specific editing effect: showing earlier or later source in a clip without moving or resizing it. This clearly conveys the slip-edit concept and distinguishes it from clip.move and clip.trim, though it does not explicitly differentiate it from siblings such as clip.slide or clip.roll.

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?

The phrase 'without moving or resizing it' gives a useful condition for when this tool is appropriate. However, it does not name alternatives like clip.slide, clip.roll, or clip.trim, so an agent must infer when to choose this tool over those siblings.

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