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

Annotations only declare readOnlyHint=false and openWorldHint=true, so the description carries useful extra weight: billing behavior (1 credit, refunded on failure), an auth prerequisite (API key), hard input limits, and result-link expiry of 7 days. It stops short of clarifying execution mode (synchronous return vs. a queued task needing get_ai_task), which is the one behavioral ambiguity left.

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 action and the result, then compactly appends cost, auth, input limits and return semantics in short clauses. No filler or restatement of the tool name.

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 spells out the return value (a link valid 7 days) alongside cost, auth and input constraints. The remaining gap is the relationship to get_ai_task — an agent cannot tell whether the link is returned immediately or after polling.

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% and both parameters already document their formats and their url-vs-base64 alternative, so the baseline is 3. The description adds the 10 MB / 2048 px constraints that apply to either input, but does not explain selection between image_url and image_base64 beyond what the schema already says.

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+resource ('Remove the background of an image with AI') and the exact output ('a PNG with transparency'), which cleanly separates it from sibling operations like ai_extend_image or ai_upscale_image. The agent knows what it produces without opening the 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?

The preconditions for use are covered (CropDen API key, accepted formats, size caps, 1-credit cost refunded on failure), so an agent can judge eligibility. However, there is no guidance on when to prefer this over siblings such as ai_extend_image or ai_upscale_image, and no mention of whether results must be retrieved via get_ai_task even though that sibling exists.

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