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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description adds real behavioral detail: endFrame is exclusive, frames are expressed in that timeline's fps, linkGroupId indicates linked A/V pairs, and `look` only appears when non-default so an untouched clip has no look key. These are non-obvious contract details an agent would otherwise get wrong.

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 the core purpose, then the copy-paste UUID workflow, then the return-shape details. It is dense but every sentence carries contract information. The clip-field enumeration is long but earns its place given the absence of an output schema.

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?

No output schema exists, and the description compensates by describing the returned structure field by field, including the conditional `look` object and frame units. Combined with annotations covering safety, an agent has everything needed to call and interpret the result correctly.

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 baseline is 3, but the description adds meaning the schema lacks: omitting timelineId returns all timelines rather than erroring, and the no-timelineId path is the recommended route when the user supplies a clip UUID. The token and projectId semantics are left to the schema, which documents them well.

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 — reads a project's timeline structure — and immediately enumerates what is returned (timelines with tracks and clips). An agent can distinguish this from mutation siblings like set_clip_properties or move_clips without opening any 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 concrete when-to-use scenario: the user pastes a bare UUID copied from the right-click menu, so call with no timelineId to match clip.id instead of guessing a name. It also states that omitting timelineId returns every timeline. It stops short of naming nearby alternatives (inspect_timeline, verify_timeline) or when not to use this tool.

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