image_prep

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

With no annotations, the description carries the full burden and does well: it discloses input formats, fit modes, dither options, a corrected-display flag, and the exact return shape including a preview upscale behavior. It does not mention error conditions or side effects, but for a non-destructive image processing tool this is adequate.

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 well-structured with an executive summary followed by a bullet-style args list and a one-sentence return description. Every line adds information; there is no filler or repetition of schema defaults.

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?

Despite having no annotations and no output schema, the description covers all five parameters, their options, and the return value in enough detail for an agent to invoke the tool correctly. It also notes an edge case (2× upscaling for small images), making it complete for the tool's complexity.

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 coverage is 0%, but the description compensates fully by explaining each parameter: source accepts path/base64/data URI, target includes named dimensions, fit explains contain vs cover, dither lists all allowed values, and corrected is described as sunlight-display preview. This is exactly the meaning the schema lacks.

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 opens with a specific, multi-verb purpose: 'Resize/letterbox an image to a named target, quantize, and preview it.' This distinguishes it from sibling tools like image_quantize by including resize, letterbox, target dimensions, and preview output.

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 clearly implies usage for image preparation to named targets, but it does not explicitly state when to use this tool versus alternatives such as image_quantize or color_nearest. There are no exclusions or alternative recommendations, so guidance is only implied.

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