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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description adds real domain behavior: tokens are split into uiControlled (editor-visible) vs code-only (invisible in the Layout Editor), and an unknown token name silently becomes an inert CSS custom property. That 'silent no-op' pitfall is exactly the kind of failure mode an agent needs. It stops short of describing the response shape or size of the vocabulary, but the output schema covers returns.

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?

Two sentences, front-loaded with the purpose before the caveat about unknown names. The first sentence is dense with parentheticals but each clause (uiControlled vs code-only vs common vs pitfalls) earns its place by defining what the caller will receive.

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 enumerate return values, and it adequately covers what the tool is for, how the tokens are categorized, and the consequence of misusing a name. Minor gap: it does not say whether the vocabulary is fixed or project-specific, which could matter when validating tokens.

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?

The tool takes zero parameters, so the baseline is 4; there is no parameter semantics to clarify and the description correctly does not invent any.

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+resource ('Returns QUESTIONSTAR's layout design-token vocabulary') and ties it directly to the sibling tool apply_layout's inlineTokens parameter. It is easily distinguished from nearby list_* siblings such as list_layout_templates, which deals with templates rather than tokens.

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?

The description makes the use context clear by naming apply_layout's inlineTokens as the consumer, implying this is a reference to consult before applying layout tokens. However, it never explicitly states 'call this before apply_layout' nor gives any when-not-to-use condition, so the routing is inferred rather than spelled out.

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