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

Annotations cover safety (readOnlyHint=false, destructiveHint=false) but the description adds genuinely non-obvious behavior: auto-verification contingent on parent-domain ownership, inheritance of the parent property's Google account, and the fact that new properties are created hidden and consume no plan slot until shown. It stops short of describing batch failure behavior or partial-success semantics for the multi-URL case.

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?

Front-loaded with the action, then constraints, then the alternative. Dense and mostly waste-free, though the dashboard/plan-slot sentence and the set_dashboard_visibility pointer add length that could be tightened.

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 3-parameter mutation tool with a full schema and an output schema, everything an agent needs to invoke correctly is present: prerequisites, domain constraint, verification behavior, visibility state, plan-slot implications, and the alternative sibling. Return values are legitimately omitted because an output schema exists.

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 description coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: parentSiteUrl is 'an existing GSC Wizard property whose Google account has access' and the new properties inherit it, plus the domain/subdomain constraint and the auto-verify implication. The max-50 and URI format are restated from the schema, so it is not a full 5.

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 and resource ('Creates one or more URL-prefix properties in Google Search Console') and names the underlying API operation (sites.add). It also explicitly distinguishes itself from the sibling add_site, which handles already-existing properties, so an agent can route between them 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?

Gives explicit when-to-use ('folder-level properties ... that do not yet exist in Search Console') and when-not ('For properties that already exist in GSC, use add_site instead'). It even points to set_dashboard_visibility as the follow-up needed to expose hidden properties, which is a real workflow cue.

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