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

Annotations already indicate readOnlyHint=true, so the tool is known to be safe. The description adds valuable behavioral detail: contrast computation against background, light/dark mode support, return fields (hex, contrast ratio, WCAG grade, usage note), and CSS custom properties. No contradiction with 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 front-loaded with the main purpose and each sentence provides distinct value: states list, contrast behavior, output fields, CSS property inclusion, and usage timing. No filler or redundancy.

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 an output schema present, return values need not be fully explained, yet the description still covers outputs, use case, and behavior. The tool has only one required parameter, and the description gives sufficient context for an agent to select and invoke it correctly. Complete for the stated 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 100%, with each parameter described. The description adds little beyond the schema; it mentions 'brand hex' and 'background colour' but these are already clear in the parameter descriptions. Baseline 3 is appropriate since schema carries the semantic weight.

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 uses a specific verb 'Generate' with a clear resource: 'WCAG-compliant UI state palette' from a brand hex. It enumerates the exact states returned and distinguishes itself from sibling palette tools by focusing on UI states and contrast compliance.

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 explicit usage context with 'Use before building any UI component system,' indicating when to invoke the tool. However, it does not explicitly mention alternatives or when not to use it, so it lacks full exclusion guidance.

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