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

Adds material context beyond the annotations: it discloses a real financial cost ('Spends Brix36 credits'), the one-picture-per-call mutation, and explains the consequence of idempotentHint ('Identical retries return the same operation without another charge'). The credit-spend disclosure is exactly the kind of information annotations cannot carry.

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 sentences, zero waste, front-loaded with the action and cost. The idempotency note is a worthwhile second sentence rather than padding.

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 values need not be explained, and annotations plus the description cover the safety and cost profile. Missing only edge-case behavior (e.g., insufficient credits, failure handling), which is minor for a confirm tool.

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 required parameters and confirmationToken are already documented in the schema. The description reinforces that draftId/quoteId must be the quoted values but adds no syntax or format detail beyond what the schema provides, making 3 the correct 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?

States a specific verb and resource ('spends Brix36 credits and starts one picture'), and its requirement of 'the exact quoted draftId and quoteId' implicitly separates it from studio_image_quote and studio_image_result. It does not explicitly name a sibling, so it falls short of 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?

Establishes a clear precondition: the customer's financial approval of the exact quoted draftId/quoteId, which implies the quote-then-confirm workflow. It gives context for use but names no explicit alternative or exclusion (e.g., versus studio_generation_confirm).

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