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

Annotations already declare idempotentHint=true and destructiveHint=true; the description reinforces idempotency with concrete semantics ('identical operationId/input retries reconcile the same edit') and adds a genuinely useful capability/cost disclosure ('No model call or credit charge'). It does not explain what the destructiveHint overwrites (the previous choice) or what happens on a revision conflict.

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 dense sentences, front-loaded with the action, then the concurrency/idempotency contract, then the cost note. No filler and nothing repeated from the schema.

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?

An output schema exists so return values need no explanation, and the description covers idempotency, revision-based concurrency, and cost. Minor gaps remain around conflict behavior and the semantics of a null choice, but nothing essential to invoking it correctly is missing.

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 80%, so most parameters are already documented. The description adds real meaning for expectedRevision (the current saved plan revision, i.e. optimistic concurrency) and operationId (stable id whose identical retries reconcile to one edit), beyond the schema's generic phrasing. The 'null' choice value remains unexplained.

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 ('Set the lip-sync choice for one saved scene') and scopes it to a single scene, which separates it from project-wide siblings like studio_film_set_speech_voice. It does not explicitly name or contrast an alternative, so it stops short of a 5.

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 mention of expectedRevision 'the current saved Film plan revision' and the retry semantics implies the read-then-write workflow, but the description never says when to use this versus siblings such as studio_sections_set_line_sync or studio_film_toggle_sound, and gives no prerequisites or exclusions.

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