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

The description describes an event notification that advances Last Frame's state ('so the next choice can appear'), which implies a meaningful side effect. However, the annotations declare readOnlyHint: true, suggesting the tool performs no state-changing work. This is an annotation contradiction, and the description does not resolve or clarify the mismatch.

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?

The description is a single, front-loaded sentence with no filler or repeated information. Every phrase earns its place: the target, the triggering event, and the resulting outcome are all conveyed efficiently.

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 one-parameter tool with an output schema, the description provides enough context to understand when and why to invoke it. It does not explain ordering relative to other Last Frame tools or how to obtain the runId, but those details are partly inferable from the parameter schema and sibling context.

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?

The parameter schema already fully describes runId as 'Last Frame run id whose current shot finished playing,' so schema coverage is 100%. The description adds no additional parameter-level detail beyond that, making the baseline score of 3 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 action ('tell Last Frame') tied to a concrete event ('current shot finished playing') and a clear outcome ('so the next choice can appear'). This uniquely distinguishes it from sibling tools like start_last_frame, type_last_frame, and timeout_last_frame based on the trigger condition.

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?

The description clearly states the usage context: it should be called when the current shot has finished playing. It does not explicitly contrast with alternatives like timeout_last_frame or type_last_frame, so it stops short of full exclusion guidance, but the triggering situation is unambiguous.

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