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

Annotations already establish that this is a non-destructive, idempotent mutation, so the description needn't repeat that. It adds genuinely useful behavior beyond annotations: new video tracks go on top, and the result is an edit result documented in server instructions. It leaves open what happens with audio track ordering and whether an identical track is deduplicated despite idempotentHint=true.

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, front-loaded with the core action and with zero filler. The placement detail and return-value pointer each earn their place.

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?

An output schema exists and the description appropriately points to server instructions for the edit result rather than duplicating it. For a simple add-track mutation with annotations covering safety and idempotency, the main remaining gap is track ordering or naming behavior for audio tracks, which is not critical.

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 50%, with the schema itself documenting preview and timeline_id. The description adds meaning for kind (video or audio) and placement of video tracks, but does not explain the name parameter, defaults, or how preview affects the returned edit result.

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 verb and resource ("Add an empty video or audio track"), and the word "empty" distinguishes it from clip-adding siblings like clip.add. It does not explicitly contrast with track.remove or track.set, but the action is unambiguous.

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?

Usage is implied by "empty" and the video/audio kind, suggesting this is for creating a track before adding clips. However, it never explicitly says when to choose this over related tools such as timeline.create or clip.add, nor does it state prerequisites.

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