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

Goes beyond the annotations by explaining the optimistic-concurrency guard (expectedRevision = current saved plan revision) and the idempotent retry mechanism (identical operationId/input reconciles the same edit), plus a cost statement. What it omits is the destructive side implied by destructiveHint=true: whether an existing actor assignment is overwritten or how reassignment behaves.

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 tight sentences: purpose first, then mechanism and cost. Every clause earns its place with no filler, and the key constraint is front-loaded.

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 annotations carry the safety profile (idempotent, destructive, non-read-only). The description covers purpose, concurrency, idempotency, and cost; the only real gap is what happens to a prior assignment on reassignment.

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 100%, so the schema already documents all six parameters, including operationId and expectedRevision semantics. The description's sentence about those two fields largely restates what the schema says, adding no new syntax or format detail, so baseline 3 applies.

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: 'Assign one available artist to one saved dialogue line.' That is unambiguous about the action and the target. It does not differentiate from the many adjacent Film siblings (e.g. studio_film_set_speech_voice, studio_film_edit_line), 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?

Usage is implied through preconditions — the line must be 'saved' and the artist must be 'available' — and it notes the operation is free ('No model call or credit charge'). However it names no alternatives and gives no explicit when-to-use/when-not guidance, leaving the agent to infer when to call this vs. editing a line or setting a voice.

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