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

The description explains the behavioral differences between fit modes (crop, letterbox, stretch), which adds value beyond the readOnly/idempotent annotations. It does not contradict the annotations.

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 mostly concise but ends with 'FREE. (FREE)', which is redundant and wastes space. This prevents a higher score.

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 the rich schema and annotations, the description adequately covers when and how to use the tool. It doesn't mention output details, but no output schema exists and the schema covers input constraints.

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 the baseline is 3. The description restates the mode semantics but does not add new parameter-level detail beyond what the schema already provides.

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 tool resizes an image to target dimensions and lists the supported fit modes. However, it does not explicitly differentiate itself from sibling tools like upscale_image, which also modifies image dimensions.

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 use-case context ('preparing images for specific platforms, thumbnails, or social media') but does not exclude alternative use cases or mention when to prefer a sibling tool.

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