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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so no safety concerns remain. The description adds valuable behavioral nuance beyond annotations: closeness is measured in OKLAB distance and means color-family similarity, not merely same hue. This meaningfully shapes agent expectations about match quality.

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 short sentences with no filler; the core behavior and matching metric come first, followed by the exact use case. Every clause contributes information.

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 description, combined with rich parameter docs and safety annotations, is largely sufficient for selecting and invoking the tool. There is no output schema, and while the detail parameter hints at row contents, the description could more explicitly state the shape of the result set; overall, the gaps are minor for a read-only search 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?

Schema description coverage is high (80%) and parameter descriptions already explain hex formats, tolerance defaults, detail levels, and maxTokens trimming. The description adds some interpretive context around hex matching (OKLAB distance, color family), but most parameter meaning is already carried by the schema, so the baseline of 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 defines the tool as returning real sites whose extracted palette is near a given hex colour, with an explicit color-matching nuance (OKLAB distance, same family not just hue). It does not explicitly contrast against siblings like find_similar or search_screens, but the color-specific language and brand-color use case make the tool's purpose unambiguous.

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 a clear trigger: 'Use when a brief names a brand colour.' This provides solid contextual guidance, though it does not state when not to use the tool or name alternative siblings, so it stops short of full exclusionary guidance.

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