Set recipe image

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

Annotations already indicate readOnlyHint=false, so the agent knows this is a write operation. The description's 'replaces' adds the behavior of overwriting the existing cover image, which is useful but minimal. It does not disclose whether the operation is idempotent (idempotentHint=false is present), whether the old image is permanently deleted, or any auth/permission requirements. The description carries some weight but does not go beyond the surface behavior.

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 a single sentence with zero wasted words: 'Replaces a recipe's cover image.' It is front-loaded with the action verb and immediately conveys the exact operation. There is no extraneous information or repetition of schema content, making it a model of conciseness.

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?

For a simple mutation tool with three fully documented parameters, an output schema, and annotations conveying read-only/destructive hints, the description is nearly sufficient. The schema explains the recipe identifier format, allowed image formats, and base64 payload constraints. The one minor gap is that the description does not state whether replacing the image also removes the old image or if there are any side effects, but this is largely covered by the word 'replaces' and the output schema. Overall, an agent has enough information to call the tool 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?

Schema description coverage is 100%, with each parameter (format, recipe, image_base64) having a clear description in the schema. The tool description itself adds no parameter-level detail. Per the rubric, when schema coverage is high, a score of 3 is the baseline; the description neither enhances nor harms parameter understanding.

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 states a specific verb and resource: 'replaces a recipe's cover image.' This clearly distinguishes it from siblings like update_recipe (which handles other recipe fields) and create_recipe, and from import_recipe_from_image (which is about importing, not replacing an existing cover). The purpose is unambiguous and immediately identifiable.

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 provides no guidance on when to use this tool versus alternatives. It does not mention that update_recipe could be used for non-image changes, or that this tool is specifically for cover images rather than other images. An agent must infer usage solely from the verb 'replaces,' which is essentially restating the tool's purpose rather than offering selection criteria.

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