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

The description discloses the important side effect that the tool 'uses this month's generation allowance' and that it films, which is beyond what the annotations provide. Annotations declare non-read-only and non-destructive; no contradiction exists.

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?

Two short sentences with no filler. The main action is front-loaded and the cost/side-effect follows naturally in the second sentence.

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 cost-incurring action with only two well-documented parameters, the description gives the essential workflow context and side-effect. It does not spell out the run lifecycle prerequisites, but the schema reference to start_last_frame and the presence of an output schema make the tool usable.

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 both parameters are documented (runId origin and 0-based optionIndex). The description adds little parameter-level detail beyond the schema, so the baseline of 3 is appropriate.

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?

The description uses a specific verb-resource combination ('Pick a numbered Last Frame option') and states the concrete effect ('films the next shot'). It is clear about what the tool does, though it does not explicitly name sibling tools or contrast itself with start/type/end Last Frame operations.

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?

Usage context is implied rather than spelled out: picking a numbered option and filming the next shot suggests it is called after a run has produced options, and the runId parameter references start_last_frame. The description does not state explicit conditions, prerequisites, or alternatives such as quote_last_frame or end_last_frame_clip.

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