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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description still adds real behavior: exact name matches rank first, and results include source attribution. It omits what happens on no match and how limit/culture affect results.

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?

Three tight sentences with the core action and output front-loaded, followed by input formats and ranking rule. Every sentence carries information; nothing is padded.

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 and three parameters, the description covers what is returned (hex/RGB plus sources), accepted input languages, and result ordering. Missing only edge-case behavior such as empty results and how culture/limit shape the response.

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 67%, and the query parameter's schema text is only 'Color name.' The description compensates well by enumerating accepted scripts and the optional 色 suffix. Limit and culture are not elaborated, but culture's schema description already points to list_cultures.

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 and resource ('look up traditional colors by name') and names the return payload ('hex/RGB with sources'). This implicitly separates it from list_colors and nearest_colors, though no sibling is called out by name.

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?

Accepted input forms (kanji, kana, English, optional 色) imply when the tool applies, but there is no explicit when-to-use, when-not-to-use, or routing to nearest_colors for fuzzy/approximate lookups.

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