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

Adds real context beyond the readOnly/idempotent annotations: account-owned managed media lease, bounded local ffprobe/ffmpeg processing, and an explicit statement that there is no AI vision or remote fetch. It also discloses the sampling behavior (first/25/50/75/last frames vs. timestamps). It doesn't state limits on duration, failure modes, or output format details, which keeps it below a 5.

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 trigger and the primary scope, then constraints, then the sibling routing. The parenthetical about judging generations is slightly wordy but earns its place by justifying the GEN-result path; overall tight for the amount of information conveyed.

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 does explain what is returned (decoded PNG frames). It covers processing locality, ownership constraints, and sampling modes. The remaining gap is behavioral detail on include_frames and max_preview_px, which an agent would otherwise have to guess.

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 description coverage is 0%, so the description carries the burden. It explains output_index (finished GEN result) and timestamps_ms (max 5) meaningfully, but include_frames and max_preview_px are left entirely undocumented, leaving 2 of 6 params with no semantic explanation.

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: inspect a video media node or a finished video GEN result in an owned Canvas project. It also explicitly separates itself from aimixer_canvas_inspect_images, so an agent can route without opening either 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 an explicit trigger ('Use when you need to see video/audio, inputs AND GEN results') plus a rationale about judging generations by their results. It names the alternative tool for images, covering the most likely misrouting case.

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