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

Annotations already declare idempotentHint=true and destructiveHint=true, and the description usefully explains the mechanism behind idempotency (identical operationId/input retries reconcile the same edit) plus the optimistic-concurrency role of expectedRevision. It also adds the cost behavior ("no model call or credit charge"), which is not derivable from annotations. It does not say what happens on a revision conflict, which is the one gap.

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 short sentences, each earning its place: purpose first, then concurrency/idempotency mechanics, then cost. No filler, no repetition of the title, and the operative 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 and annotations cover the safety profile, so the description needn't explain return values. It supplies the concurrency and retry contract an agent needs, but omits failure behavior when expectedRevision is stale, which matters for a destructive revision-guarded write.

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%, so the baseline is 3, but the description goes beyond per-parameter text by explaining how expectedRevision and operationId work together for concurrency and safe retries. It adds real semantics rather than restating the schema.

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: "Replace the text of one saved dialogue line." That cleanly separates it from sibling mutators like studio_film_add_line and studio_film_remove_line by implication, but it never names an alternative explicitly, so sibling differentiation is left to inference.

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 implies usage context (revising an already-saved line, retries via operationId) and notes no model call or credit charge, which hints at when it is cheap/safe to call. However, it gives no explicit when-to-use/when-not guidance and never routes the agent to studio_film_read first or contrasts with add/remove alternatives.

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