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

Annotations only provide false hints for read-only/destructive behavior, and the description adds little behavioral context. It doesn't state how the generated image is returned (binary, URL, saved file), whether any server-side storage occurs, or what side effects, if any, exist. The schema mentions response MIME, but the tool description itself is thin on 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, front-loaded sentence that names the action, the resource, and the main customization options, followed by a useful [category: generate] tag. There is no filler or redundant explanation.

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?

The parameter schema is rich and covers the input side well, but there is no output schema and the description does not explain what the tool returns or how the generated image is delivered. For a tool with six optional parameters and no required inputs, an agent would benefit from knowing the response shape or storage behavior.

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's phrases like 'any dimension' and 'custom background colour and label text' broadly map to parameters, but they don't add meaning beyond the schema's already detailed per-parameter descriptions, which include defaults, clamping behavior, and exact field names.

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 ('Generate') and a specific resource ('placeholder image'), and further clarifies the key options: any dimension, custom background colour, and label text. This clearly distinguishes it from sibling tools like generate_qr_code, generate_barcode, or photo_resize.

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 a clear context for use—creating placeholder images with custom dimensions, colors, and text—but it does not explicitly say when not to use it or mention alternative tools. Usage is implied by the resource type rather than explicitly routed.

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