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

Annotations already establish read-only, idempotent, closed-world behavior, and the description usefully adds that returned values are oklch() in v4 and hex in older versions. It says nothing about failure behavior for unknown color names, which is the remaining behavioral gap.

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, front-loaded with the core action and scope before the usage directive and format note. No redundant or filler content.

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?

An output schema exists, so return values need no elaboration, and annotations cover the safety profile. For a two-parameter lookup tool this description supplies everything an agent needs to call it correctly.

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 100%, so both parameters are already documented, including the version enum. The description's version/format note (oklch in v4, hex earlier) adds a little meaning but does not go beyond what the schema already conveys about accepted inputs.

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 ("Looks up Tailwind's own default colors") and qualifies scope precisely (a whole color or a single shade, across v1-v4). It does not explicitly distinguish itself from the siblings find_closest_tailwind_color and generate_palette, so it stops short of a 5.

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?

"Use it instead of writing default Tailwind color values from memory" gives a clear condition for reaching for this tool. It names no alternative tool and no exclusion case, so it lacks the explicit when-not routing that would earn a 5.

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