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

Annotations already declare non-read-only, open-world, non-idempotent behavior. The description adds genuinely new behavioral context beyond annotations: dual billing paths (OAuth credits vs API-key USD) and, importantly, that the tool quotes a price before committing spend. It does not describe the return format or async job behavior, but for an annotation-backed definition this is solid added value.

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: the functional purpose is front-loaded, followed by the commercial/billing constraint. Every clause earns its place.

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 9 parameters, a nested image object, and no output schema, the description covers purpose and billing but says nothing about what the agent gets back (an edited image? a job id?), whether the call is synchronous, or what the quoted-price confirmation flow looks like end to end. Adequate but with clear gaps for a tool of this complexity.

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 every parameter including max_usd, currency, image vs image_url split, and more_image_urls is already fully documented in the schema. The description adds no parameter-level detail beyond what the schema provides, which is the correct baseline-3 case.

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 ('Change a photo') plus concrete examples of the edit types it supports (style, outfit, background, add/remove). It implicitly distinguishes itself from narrow siblings like erase_object, remove_background, or relight_photo, but never names an alternative, so it falls short of a 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?

The prompt-based editing use case is implied clearly by the examples, and the billing modes are noted. However, there is no explicit guidance on when to choose this over siblings such as create_image or erase_object, and no exclusions or prerequisites stated.

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