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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description goes further by disclosing that editing-tool pricing inspects the media exactly as the real tool does, needs the same generate permission, and is limited like the tool. It also explains that the result carries max_coins used by confirmation and affordability checks — real behavioral context beyond the annotations. Minor gap: no statement about what a pricing failure or over-limit request looks like.

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 action and then the two calling modes; every sentence carries information. It is dense and slightly long for a single description, but nothing is 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, the description need not explain return values, yet it still calls out max_coins and the affordability comparison, so the agent understands what the call is for. Complete enough for correct invocation, with only failure-mode detail left out.

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 schema carries parameter documentation. The description still adds meaning the schema does not: that tool and input are alternatives to media and items, and that input accepts the same arguments as the tool you would call, with request_id and confirmation_token ignored. That is genuine semantic guidance rather than repetition.

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 — price generations exactly, without submitting — and names its relationship to generate_image / generate_video and the editing tools. An agent can tell this apart from the sibling generation tools immediately because the description says it is the dry-run counterpart.

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 explicit routing: pass media and items for generate_image / generate_video, or tool and input to price an editing tool, and names all eight editing tools. It also flags the exclusions an agent would otherwise get wrong (nothing is submitted or charged, unlimited-plan allowances do not apply).

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