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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world. The description adds genuinely new behavioral context beyond them: it validates against the current storyboard state and explicitly scopes the operation with 'No approval, generation or spending,' telling the agent exactly where its authority ends. It stops short of describing any failure/validation semantics.

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, front-loaded with the verb and the object, ending with a scoping negation that prevents misreading. No filler or redundant restatement of the title.

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?

With an output schema present and safety annotations supplied, the description does not need to explain return values or side-effect safety. It covers the operation's scope and limits adequately; only the routing against sibling redo/quote tools is left unspecified.

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 both parameters are already documented; the baseline is 3. The description adds marginal framing by noting stableShotId is 'widget-selected' and must match the 'current visible storyboard,' but it provides no additional syntax or constraint detail beyond 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?

The description states a specific action (validate a widget-selected stableShotId against the current visible storyboard) and its outcome (return a request to price that picture change). It clearly frames the tool as a pricing-request step, but it never names or contrasts the nearest sibling such as studio_storyboard_picture_changes_prepare, so sibling differentiation is only implicit.

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?

It implies the trigger context (a widget-selected stableShotId on a visible storyboard) and the downstream purpose (pricing a picture change), which is useful implied usage. However, it never states when to prefer this over adjacent tools like picture_changes_prepare or the various quote endpoints, so an agent must infer the boundary.

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