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

Annotations already cover read-only, idempotent, non-destructive behavior, and the description adds meaningful specifics: normalized values, only facets with at least one other match, and FREE. This goes beyond what annotations communicate without contradicting them.

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?

The description is three concise sentences with the core purpose front-loaded and no filler. Every sentence adds information: what is returned, what similarity means, and the inclusion filter.

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 simple one-parameter, read-only tool with a rich output schema and strong annotations, the description covers purpose, scope, filtering behavior, and constraints. Nothing critical is missing for invoking 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 coverage is 100% and the only parameter's description already says it is the source webmaster UUID from search_webmasters. The tool description adds no additional parameter semantics, matching the baseline for high schema coverage.

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 uses a specific verb ('List') and a concrete resource ('URL-parameter keys and normalized values') and clarifies that similarity means shared affiliate/tracking parameter values, not name or domain similarity. This distinguishes the tool from similarity-oriented siblings such as find_similar_webmasters.

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 gives clear context: use it to get URL-parameter facets for related webmasters, and explicitly excludes name/domain similarity. It doesn't name a sibling alternative like find_similar_webmasters or state a when-not condition beyond the similarity definition, so it falls 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.