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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered structurally. The description adds the useful behavioral detail of what counts as a duplicate (URL-prefix plus domain property for the same domain), but says nothing about scope, e.g. whether it scans all sites in the account or a subset.

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?

A single front-loaded sentence with no filler; the defining criterion is stated immediately. Nothing could be removed without losing meaning.

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, return values need no explanation, and there are no parameters to document. The remaining gap is scope — whether the scan covers all accessible sites or only some — but for a zero-arg read-only detector the definition is otherwise sufficient.

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 are no parameter semantics to explain and the baseline of 4 applies. Nothing in the description misleads about inputs, and the absence of arguments is consistent with the empty schema.

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 ('Find') and a precise resource ('domains registered as both URL-prefix AND domain properties'), and the definition of 'duplicate' is spelled out rather than left to inference. It is clear what the tool returns conceptually, though it does not explicitly contrast itself with the nearby list_sites or get_site_details siblings.

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?

Usage is only implied: an agent can infer this is the tool to run when auditing Search Console property configuration, but there is no explicit 'use this when' statement, no prerequisites, and no named alternative such as list_sites for enumerating properties.

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