contrast_check

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

Since no annotations are provided, the description carries the full burden. It discloses the core behavior (computes contrast and reports compliance levels) but does not mention return format, error handling, or that it is a read-only operation. It adds some context beyond the schema but remains minimal for a tool with zero annotation coverage.

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 short sentences with no filler. The purpose and outcome are front-loaded in the first sentence, and the compliance details add necessary context in the second. 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?

For a simple two-parameter tool without an output schema, the description should clarify what the agent receives. It states 'Reports AA/AAA compliance' but does not specify whether the numeric contrast ratio is also returned, nor does it mention error handling for invalid color formats. This is a significant gap for successful invocation and result interpretation.

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 descriptions for both parameters ('First color (foreground)' and 'Second color (background)'), so the description adds no additional parameter meaning. The baseline of 3 applies when the schema fully documents parameters, and the description does not need to supplement it.

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?

States the specific verb 'Check' with the resource 'WCAG contrast ratio between two colors' and clearly differentiates from sibling tools like color_convert, palette_generate, color_mix, and css_gradient. The additional mention of AA/AAA compliance for text and UI components further clarifies the purpose.

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 needing contrast ratio/compliance) but does not explicitly state exclusions or alternatives. While the purpose is self-evident and distinct from siblings, there is no guidance on when not to use it or that other tools should be used instead for different color operations.

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