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

Annotations already declare readOnlyHint=true, so the safe, non-destructive nature is covered. The description adds that the tool returns contrast ratios and pass/fail grades per combination, which provides some output context. No additional behavioral traits (e.g., auth needs, rate limits) are disclosed, but with annotations present, the burden is lower.

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?

Two concise sentences. The first states the action and output; the second provides usage guidance. No wasted words, and front-loaded with the core function.

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 simplicity (one parameter) and existence of an output schema, the description covers the purpose, alternative, and summary of outputs. It lacks mention of error handling or default behavior but is sufficient for a straightforward 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 has 100% coverage with a detailed description of the 'palette' parameter as an array of hex values. The description does not add extra meaning beyond confirming it accepts a palette. Thus, baseline 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 accepts a palette array and returns contrast ratios and pass/fail grades for every foreground/background combination. It explicitly contrasts with sibling 'accessibility_check' by recommending this tool instead of multiple calls, effectively distinguishing its batch 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 provides a clear alternative: 'Use this instead of calling accessibility_check multiple times for a palette.' This guides the agent to choose this tool for full-palette analysis. However, it does not specify scenarios where the matrix might not be needed (e.g., single combo check), slightly reducing completeness.

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