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

Annotations already declare read-only/idempotent/no destruction, and the description adds real behavioral content beyond them: nothing is charged, a price mismatch causes refusal on create_visual, a set (batch 2-4) prices the same as a single image, and a carousel is one flat price regardless of slide count. That pricing-invariance behavior is not derivable from any structured field.

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?

Front-loaded with the core promise ('Price an image job without spending') and only four substantive sentences with no filler. The trailing pricing rules are dense but each earns its place; slight denseness keeps it from a 5.

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?

For a 7-parameter, 2-required quote tool with no output schema, it covers the purpose, the workflow hand-off, the parameter-matching requirement and the return field name (`credits`). It stops short of describing the rest of the response or any failure/prerequisite conditions beyond mismatch refusal.

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 71%, so the schema carries most parameter documentation, but the description adds the crucial constraint that the parameter set must mirror what will be sent to create_visual, plus pricing semantics for `batch` and `creative_kind`=carousel. It leaves brand_id and user_goal unaddressed, so 4 rather than 5.

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?

Uses a specific verb ('price/quote') on a specific resource ('an image job') and immediately scopes it against its sibling create_visual by stating it does not spend credits. An agent can tell it apart from create_visual and from the planning siblings (plan_image_concepts, plan_logo) without opening 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?

Gives a clear context of use and a concrete follow-on contract: pass the returned `credits` as `expected_credit_cost` on create_visual, and a mismatch is refused. It also requires sending the same creative_kind, tier, batch, visual_type and references_count used later. No explicit 'when not to use' or comparison to other plan_* siblings, so it stops short of a 5.

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