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

readOnlyHint=true already tells the agent this is a safe read, so the description only needs supplementary context. It adds the useful scoping detail that the conventions are project-specific ('in this project'), but says nothing about volume, applicability, or whether the rules are prescriptive or advisory.

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?

One compact sentence with no filler, and the subject matter listed up front. It is a fragment rather than a complete statement, which costs a little clarity but wastes no words.

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?

For a zero-parameter, non-destructive fetch with no output schema, the description covers the topic scope adequately. It leaves unresolved what the returned rules look like and how strictly they should be applied, which is the main open question an agent would have before calling it.

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 there is nothing for the description to disambiguate; the baseline of 4 applies. The description correctly does not invent parameter detail.

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?

The description identifies the resource (design conventions for Caliper UI: tokens, hierarchy, focus, motion, interface copy) but is a noun phrase with no verb, so it never states that the tool retrieves/returns them. The content enumeration does distinguish it from component-lookup siblings, but the phrasing is closer to a topic label than an action statement.

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?

It implies the trigger condition ('when building UI with Caliper UI in this project'), which is genuine contextual guidance. It gives no explicit when-not or named alternative, and does not say whether to call it before starting UI work versus on demand.

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