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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the read-only safety profile is covered. The description adds genuine context beyond them: anatomy is read from the live DOM, results are a ranked per-product panel, and it discloses the fallback behavior when no component matches. It doesn't mention caching or refresh semantics, which keeps it from a 5.

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?

Purpose and the pre-build trigger are front-loaded, then args. The divergence illustration (Linear's pill+shadow vs Vercel's shadowless pill) is somewhat verbose but earns its place by showing what the output looks like.

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 still explains the return shape (one ranked panel per product with measured padding/radius/border/shadow/weight/hover) plus the no-match fallback. An agent has everything needed to call it and interpret the result.

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 0%, so the description must carry the parameters — and it does: component_type with six concrete examples, industry with example values, scheme as "dark"/"light" including the meaningful note that it matches the measured background, and limit with its range (1-12) and default (8).

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 (compare) and resource (UI atoms across products), and even distinguishes itself from data-fetching siblings by emphasizing cross-product, live-DOM anatomy. An agent can tell it apart from get_component or compare_sections 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?

"Use before building any component" gives an explicit trigger context. It does not, however, name the alternative (e.g. get_component for a single product) or state when not to use it, so it stops short of full routing guidance.

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