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

The description adds meaningful behavioral context beyond the readOnlyHint annotation: it is deterministic, has no LLM cost, and returns a predefined set of rule categories. This helps the agent anticipate the tool's performance and output, though it does not discuss edge cases or failure modes. 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 two sentences, front-loaded with the primary action and output list. The final note 'Deterministic, no LLM cost' is concise and provides useful selection information without padding. Every word earns its place.

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 tool's simple input (one array) and the presence of an output schema, the description sufficiently covers the purpose and behavior, including output categories. It lacks an example or clarification of the 'WCAG matrix' phrasing, but the combination of schema and description is reasonably complete for an agent to select and invoke the tool.

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?

The input schema already fully describes the only parameter ('palette' as an array of hex values) with 100% coverage. The description adds little beyond the ambiguous phrase 'palette WCAG matrix', which might confuse the input format. Since the schema carries the parameter meaning, a baseline of 3 is appropriate.

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's function with a specific verb ('Convert') and resource ('a palette WCAG matrix'), and enumerates the distinct output types (safe pairs, AA-only pairs, etc.). This distinguishes it from sibling tools like accessibility_matrix, which likely produces the matrix rather than the rules.

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 implies when to use the tool: when you have a palette and need actionable design-system rules. It also adds a decision factor with 'Deterministic, no LLM cost', suggesting it is a reliable and low-cost option. However, it does not explicitly mention when not to use it or name alternative tools, so it stops short of a full when/when-not guide.

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