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

Annotations already declare readOnly, idempotent, closed-world, so safety is covered. The description adds that a suggested fix is returned and that hue is preserved, which is useful non-obvious behavior. However it doesn't say what the fix looks like (adjusted lightness? nearest passing pair?) or what happens on honestly-unfixable pairs.

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?

A single efficient sentence that front-loads the operation and packs the metrics and fix into the same clause. It could be slightly longer to explain the fix behavior, but no sentence is wasted.

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?

Two required params, no output schema, and the description names the outputs (ratio, Lc, suggested fix), which is the essential piece an agent needs since there's no output schema. Missing only granular detail on the fix and threshold semantics.

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% and both params document hex format with validation patterns, so the schema carries the load. The description adds nothing about accepted input forms beyond what's already in the schema. Baseline 3.

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+resource (check text/background contrast) and enumerates the exact metrics returned (WCAG 2 ratio, APCA Lc) plus the remediation offered (suggested fix preserving hue). This distinguishes it clearly from siblings like convert_color or generate_harmony, which don't evaluate contrast.

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 usage — verifying color pairs against accessibility standards — but never states when to prefer it over siblings or any prerequisites. No exclusions or alternative routing are given.

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