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

Annotations already declare read-only/idempotent/non-destructive, and the description goes well beyond them: the server derives a missing operationId, new_version reuses a stable op_ ID, retries retain the originally quoted revision, a short balance returns credit information only, and the result is a signed picture-only quote with exact confirmation fields. These are non-obvious behavioral traits an agent could not infer from the annotations.

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?

Purpose and the no-spend guarantee are front-loaded, and the sentences are short and individually informative. The block is dense with clause stacking ("bound to the current revision, quality and stableShotIds"), which costs a little readability but no sentence is pure filler.

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, return shape need not be spelled out, and the description still covers mode selection, revision binding, idempotent retries, approval handling and insufficient-balance behavior. Remaining gaps are minor (no explicit pointer to the confirm tool as the follow-up step).

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 86%, so the baseline is 3, but the description adds rules the schema does not: operationId is derived server-side when omitted, and lookTest:true binds the call to the saved bounded key-look set. The mode and quality explanations largely restate the enum descriptions, keeping this just above baseline.

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?

Opens with a specific verb+resource and an explicit non-effect: "Prices selected storyboard pictures without spending." It also draws the boundary against the whole video/planning family ("This quote covers no video or planning model"), so an agent can separate it from studio_video_plan, studio_image_quote and the sibling confirm tool without reading 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?

It states the pre-spend context and the conditions under which each mode applies ("missing" vs "new_version for exactly one existing picture"), plus that chat approval and existing confirmation codes are accepted. It never explicitly names studio_storyboard_stills_confirm as the execution step, so the when-to-use-vs-sibling routing is implied rather than stated.

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