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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it returns a JPEG, it moves the playhead as a side effect, and clip mode isolates a single clip's crop/grade/effects with nothing in front or behind. The playhead side-effect disclosure is a meaningful addition.

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-loads the core purpose (composited picture as JPEG) and keeps to three compact sentences. The em-dash-heavy parentheticals are slightly dense but each clause carries distinct information (clip isolation, multicam), so little is wasted.

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 no output schema, the description correctly states the return format (JPEG) and the playhead side effect. It also covers the non-obvious clip behavior. Only missing details like resolution defaults relative to the width param (which the schema already documents) keep it from a 5.

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. The description nonetheless adds semantics beyond the schema for 'clip' — that it shows the clip's crop, grade and effects alone, with nothing over or under it — and explains that 'time' drives the playhead position. This goes beyond the schema's terse parameter text.

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: returns the composited timeline picture at a given time as a JPEG. It also distinguishes the 'clip' mode (one clip alone) from the full composite, and notes the multicam use. It does not, however, explicitly differentiate itself from close siblings like view_media_frame or view_contact_sheet.

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 clear context for use — checking framing, text, colour and layout — and a secondary use case (viewing an off-air multicam angle). No when-not conditions or named alternative tools are provided, so it stops short of full routing guidance.

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