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

Annotations already establish read-only/idempotent safety, and the description goes well beyond them: it discloses the free/no-credit billing model, the meaning of error rows (URL not actually measured), and the semantics of UNKNOWN as Google's own non-determination. These are exactly the traps an agent would otherwise misreport.

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 purpose and the triggering question, then the caveats. It runs slightly long, but the error-row and UNKNOWN guidance each prevent a real reporting mistake, so almost every sentence earns its place.

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 carries the return-value burden and does so: it describes the row-per-URL result shape, the error field, and how to count inspected URLs correctly. Nothing needed to call or interpret the tool is missing.

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 projectId, urls, and languageCode are already documented in the schema; the description only restates the 1-10 property-scoped URL constraint. That is the baseline 3 when the schema carries the load.

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+resource (Google Search Console URL Inspection) and enumerates what is returned: index/coverage state, last crawl time, canonical selection, mobile/rich-results verdicts. It is clearly distinct from sibling GSC report tools like get_search_console_coverage because it is explicitly per-URL.

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 a concrete triggering question ('is this page indexed? why not?') and notes the 10-URL cap and property scoping. It never names an alternative tool for bulk coverage questions, so the when-not-this-tool case is left to inference.

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