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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely new behavioral context on top of that: it is free, deterministic, never starts a project or paid task, and it asserts a substantive domain constraint that Consumer App/browser measurements cannot be substituted with model API results.

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?

Three tight sentences, front-loaded with the core purpose, then the cost/behavioral guarantee, then the key measurement constraint. Every sentence carries information and none repeats the schema or annotations.

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 7-required-parameter tool with no output schema and no parameter descriptions, the definition covers inputs reasonably but never says what the check returns (a match/mismatch verdict, unsupported-field reasons, or a suggested alternative), nor what an agent should do on a negative result. That return-value gap matters more here precisely because no 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 0%, so the description carries the burden, and it does enumerate the semantic dimensions (intent, target, measurement surface, language, market, deliverables) that map onto six of the seven required parameters. It also adds an enum-level rule for desired_surface (no substitution of consumer app/browser with model API). It stops short of explaining intent enum values, the deliverables format, or request_ref.

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 opens with a specific verb+resource: 'Check whether a GEO intent, exact target, measurement surface, language, market and deliverables are supported.' The clause 'never starts a project or paid task' distinguishes it from siblings like geo_create_project and geo_quote_observation without needing to open either 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?

It gives clear preconditions for calling: the check is free and deterministic and does not launch a project or incur cost, which implies it is a pre-flight gate before the paid/project tools. However, it never names an alternative sibling explicitly (e.g. geo_quote_observation or geo_create_project) as the next step, so routing is left partly to inference.

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