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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real value beyond them by disclosing the return contents (shade scale, contrast checks, CSS/JSON/Tailwind exports) and a scope caveat about contrast measurement limits.

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: capability and input first, then outputs, then the limitation and the follow-up call. Every sentence earns its place with no filler.

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, the description compensates by enumerating the return artifacts, and annotations already cover safety and determinism. Purpose, input, outputs, limitation, and next step are all present for a simple single-parameter 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 0%, so the description must carry the parameter meaning, and it does: the input is a 'six-digit hex brand color', which matches the schema pattern and explains the format's intent. Minor gap: it doesn't clarify case handling or whether the '#' is required, though the pattern implies it.

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 (Generate) and resource (light and dark semantic color tokens) plus the exact input form (six-digit hex brand color). No sibling tool overlaps with color-token generation, so no disambiguation is required.

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?

Gives a clear usage boundary ('This measures listed color pairs only, not whole-page accessibility') and a concrete next step ('Call usesignal_open_workbench with the result input to preview'). It lacks an explicit when-to-use-vs-alternatives statement, but no sibling competes, so the context is sufficient.

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