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

With no annotations, the description carries the burden and does well: it discloses that it renders the real timeline composition, avoids exporting the entire video, and does not mix audio — all meaningful cost/scope traits. It is missing only auth/permission requirements and how the inspected frame is delivered back.

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 sentences, each earning its place: what it does, what it is for, and what it is not for. The core purpose is front-loaded and the routing guidance follows immediately.

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 read/render tool with no annotations and no output schema, the description covers purpose, scope limits, and alternatives well. The main residual gap is not saying what the caller receives (frame image, URL, or analysis), which matters given there is no output schema to explain the return.

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% and all three params are documented in the schema, so the baseline is 3. The description reinforces 'exact timeline time' but adds no format or constraint detail beyond what the schema already provides (e.g., the 12.5 seconds example).

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+scope: 'Render and inspect the final composed frame of an edit at an exact timeline time.' It immediately distinguishes itself from siblings by naming watch_video and review_edit as the tools for motion/pacing/sound.

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?

Explicitly frames this as the 'fast visual spot-check' for static attributes (typography, overlays, framing, transitions) and states the when-not condition: use watch_video or review_edit when motion, pacing, or sound must be judged across time. Alternatives and selection criteria are both named.

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