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

With no annotations, the description carries the full disclosure burden. It does disclose the key behavior that a new PNG asset is created (a side effect, not a read), but says nothing about cost/credits, synchronous vs. asynchronous execution, permissions, or what happens on an out-of-range timeMs.

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 the crucial timeMs caveat, then the follow-up routing. No filler; "Grab" is informal but not ambiguous.

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?

There is no output schema, and the description does not say what is returned — notably whether the new asset's ID comes back in the response, which matters for the very chaining it recommends. Coverage of inputs and behavior is adequate but leaves this meaningful gap.

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 should compensate for all three parameters. It only explains timeMs (video-relative, not timeline position), leaving projectId and assetId to inference; they are self-evident names, but the compensation is incomplete.

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 ("Grab one frame of a video asset") plus the concrete output ("a new PNG image asset"), which is much more than a restated name. It does not explicitly contrast with lookalikes such as asset.get or shot.generate_keyframe, so sibling differentiation is only partial.

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?

Provides clear usage context and, unusually, names three downstream tools (shot.add_still, location.add_reference, character.add_reference) that consume the result, which tells the agent what to do next. It stops short of stating exclusions or prerequisites (e.g. when to prefer shot.generate_keyframe).

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