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

The description adds cost information ('$0.10 per image') and output type ('transparent PNG') beyond the annotations, which only state readOnlyHint=false and openWorldHint=true. This is meaningful behavioral context that the agent needs to decide whether to invoke the tool. However, it does not disclose potential failure modes or edge cases, so it is not a full disclosure.

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?

The description is two short sentences, front-loaded with the core action and output, followed by the cost. Every word adds value; there is no redundancy or filler, making it highly concise and well-structured.

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 no output schema, the description correctly specifies the return format ('transparent PNG') and includes the cost, which is essential for agent decision-making. Since the tool has only one parameter already documented in the schema, the description covers all necessary context for an agent to call it correctly.

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?

The input schema already fully describes the sole parameter ('image' as a public https URL or base64 data URI) with 100% schema description coverage. The tool description adds nothing about parameter usage or format, so it does not surpass the baseline of 3.

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?

The description clearly states the action ('Cut out the subject'), the resource (input image), and the output ('return a transparent PNG'), which precisely differentiates it from siblings like remove_watermark. The verb and resource are specific and unambiguous.

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 description gives no explicit guidance on when to use this tool versus alternatives. It does not mention conditions or exclusions, nor does it reference any sibling tools. While the purpose implies usage for background removal, the lack of any comparative context leaves the agent to infer the appropriate scenario.

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