Suggest a passing color

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the tool is safe and non-destructive. The description adds key behavioral context: it returns a 'mathematical candidate' and explicitly states it is 'not an automatic edit.' This goes beyond annotations by clarifying that the user must apply the suggestion themselves, fully disclosing the tool's scope.

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 long, each sentence earns its place. The first sentence states the core function concisely; the second clarifies the non-destructive, advisory nature. No wasted words.

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 tool has 6 parameters (2 required, 2 enums), moderate complexity. The description explains the what and the result, but lacks details like what happens when no adjustment can reach the threshold (returns null/error?). Additionally, there is no output schema, so the return format is left to experimentation. For a mathematical suggestion tool, the description is largely complete, but could mention error handling.

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 only 33%, meaning the schema documents only two parameters (foreground, background) with descriptions. The description adds meaning by explicitly mentioning 'black-or-white-directed' adjustments and connecting parameters to WCAG thresholds. It does not detail each parameter beyond what the schema provides, but for the low coverage, it compensates well by explaining the tool's purpose. The enum parameters (level, adjust) are left for the schema to define, which is acceptable given the tool's focused purpose.

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 specific verbs ('Find', 'adjustment') and resources ('foreground', 'background', 'WCAG contrast threshold'). It clearly identifies the tool's output as a mathematical candidate, distinguishing it from automatic edits and sibling tools like check_contrast or explain_issue.

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 does not explicitly state when to use this tool versus alternatives like check_contrast or get_wcag_checklist. However, the mention of 'nearest...adjustment that reaches the selected WCAG contrast threshold' implies it is used when a user needs a suggestion to fix contrast, and 'Returns a mathematical candidate, not an automatic edit' distinguishes it from an auto-fix. No explicit exclusions are given.

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