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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing the breadth of the audit: contrast tiering (body/large/decoration), CVD confusion detection, and out-of-sRGB flagging. It does not describe the response shape, but that is a minor gap given the read-only nature.

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 sentences, front-loaded with the action verb and a tight comma-separated enumeration of checks, followed by a single usage directive. No filler or redundant restatement of the name.

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 no output schema, the description carries the burden of conveying what comes back, and it does so reasonably by naming the classifications (safe for body/large/decoration, CVD-confusable pairs, out-of-sRGB colors). It stops short of describing structure or severity detail, but an agent has enough to call it and interpret the intent.

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 100% and the single 'colors' parameter is thoroughly documented with accepted formats and a 2-12 count. The description adds nothing about parameters, so the baseline of 3 is correct when the schema does all the work.

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 a specific verb ('Check') and resource ('every text and background pair in a palette') and enumerates the exact analyses performed (WCAG 2, APCA, CVD, sRGB gamut). This clearly separates it from siblings like check_contrast, simulate_cvd, and check_gamut, which each do a subset.

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 final sentence gives clear timing guidance ('Use it before shipping a theme or chart palette'), which is meaningful context for when to reach for this tool. However, it never names alternatives or exclusions, so an agent must infer whether to prefer this over check_contrast or simulate_cvd for narrower tasks.

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