Remove background from image (Recraft + fal.ai BiRefNet v2 fallback)

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

Discloses credit cost, auto-fallback between providers, and performance on different input types. Adds significant context beyond annotations, which only set openWorldHint=true and no destructive hints.

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?

Four sentences, front-loaded with main action. No fluff. Each sentence adds value.

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?

Given single param and no output schema, description fully explains purpose, usage, cost, fallback, and limitations. Agent can correctly decide to use this 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 covers 100% of the single parameter with description. Description adds 'public' qualifier but not much else. Baseline 3 is appropriate.

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?

Clearly states it removes background and returns PNG with alpha. Distinct from siblings like remove_background_video. Specific verb+resource.

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?

Provides use cases (product shots, etc.) and limitations (transparent PNG). Lacks explicit when-not-to-use compared to alternative tools like edit_image, but covers fallback behavior and credit cost.

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