play_animation

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

Goes well beyond the annotations by disclosing the exclusive-ownership lock, the rejection of edits while active, the 'never advances frames with a script' constraint, and the pending return that must be closed with stop_animation. It does not explain what state makes destructiveHint=true, which is the one gap for a mutation-flagged tool.

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?

Four short sentences, front-loaded with the action and its main constraint, and every sentence carries information. The 'Timeline.Play' jargon is slightly dense but not wasteful.

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 cryptic 'Returns pending' line does not tell the agent what a successful call yields or how to poll. Combined with fully undocumented parameters, the definition is serviceable for invocation but leaves real gaps for a stateful, lock-taking operation.

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% and the description only implies a bounded range via 'bounded'; it never explains scene_id format, whether start_frame/end_frame are inclusive, why the maximum is 120, or the start/end relationship. With three undocumented required params, the description does not compensate for the coverage gap.

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 ('Start a bounded native Timeline.Play observation') with scope ('on a stopped scene') and explicitly separates itself from the sibling stop_animation by naming it as the required follow-up. An agent can distinguish it from set_current_frame/set_keyframe without opening any 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 clear preconditions ('stopped scene', 'requires exclusive playback ownership', 'rejects edits while active') and routes to stop_animation for measurement. It stops short of an explicit when-not-to-use rule (e.g. use set_current_frame for single-frame scrubbing), so it is clear context without full alternatives coverage.

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