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

With annotations fully absent, the description carries the entire behavioral burden and does so thoroughly. It discloses the LIGHT/DARK PAIR semantics, quantization error from 8-bit hex storage, deterministic/read-only nature, and the refuse-rather-than-clamp failure mode with rejection reasons.

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?

Though longer than one-liner, every sentence contributes distinct information: core operation, parameter semantics, conceptual use case, output details, precision limitation, and failure behavior. The core purpose is front-loaded, and the additional explanation is dense rather than 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?

The description is complete for a two-parameter tool: it defines inputs, return content, error behavior, determinism, and the conceptual application. Even with an output schema present, it adds necessary context about the quantization error and refusal behavior that an agent could not infer from the schema alone.

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 0%, so the description must explain both parameters, and it does. It specifies color's accepted formats (hex, CSS name, RNV brand name, saved-palette reference) and lightness as a list of L* values in 0-100, adding meaning the raw JSON Schema completely lacks.

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 opens with a clear verb and resource: 'hold hue and chroma and set lightness, returning one result per requested L*'. It explicitly contrasts with mix_colors by stating the same-color vs. different-color use case, so an agent can differentiate it from its siblings without reading schemas.

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?

It gives explicit when-to-use guidance: 'Use it when you need the same color at a different lightness; use mix_colors when you need a different color.' It also provides important behavioral context about read-only/deterministic operation and refusal instead of clamping, which helps the agent decide when this tool is appropriate.

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