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

Adds real context beyond the annotations: determinism (same input, same output) and hard limits (64 KB JSON input, 1 s per call, 1 MB result), plus the algorithmic behavior (OKLCH lightness varied at constant hue). The 'read-only, no network access, no stored state' clause largely restates readOnlyHint/openWorldHint/destructiveHint, so it is not maximally additive, but the limits and determinism are genuinely useful.

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?

Front-loaded with the core behavior, then neatly labeled blocks (Cuándo/No para/Efectos/Determinista/Límites, then the EN mirror). Every clause carries information, but the full bilingual duplication roughly doubles length and pushes the limits section well past the leading description of what the tool does.

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 an output schema present, the description need not describe return values, and it covers the remaining gaps: algorithmic basis, both operating modes, when to prefer it over siblings, determinism, and resource limits. Nothing an agent needs before calling is missing.

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%, so baseline is 3, but the description adds genuine meaning: it explains that omitting the end color produces a 50-950 scale and that 'steps' controls ramp granularity in OKLab. Color-space details (OKLab vs. OKLCH hue-constant) are semantics the schema does not convey, though input format details (hex support) are left implicit.

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 ('Builds an evenly spaced color ramp between two colors in OKLab... or a 50-950 design-system scale from one brand color') and names the color space and construction method. It also explicitly rules out the nearest sibling ('Not for: parsing any common CSS color (color-convert)'), so an agent can distinguish it without opening a schema.

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?

Provides an explicit 'When:' condition (exact color values, contrast, palettes, e.g. accessibility checks) and a 'Not for:' exclusion routing to color-convert. The two modes (two-color ramp vs. single-color scale) are also clearly conditioned on whether an end color is supplied.

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