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

Annotations already declare readOnly/non-destructive/non-open-world, so the safety profile is covered. The description adds real behavioral context beyond that: a 300s tenant cache, a per-call limit of 50 names, and the caveat that queryable fields are not necessarily mutable. It does not describe rate limits or failure modes, so not a 5.

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?

Two tightly packed sentences, front-loaded with the capability and limit before the caveat. No filler; every clause adds information.

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?

No output schema, so the description appropriately enumerates the returned metadata types, which is helpful. However it leaves one of three parameters undocumented and gives no pagination or error behavior. Adequate but with visible gaps for a lookup tool an agent will chain into query building.

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 33% (only customer_id documented), so the description must compensate and only partially does. 'Up to 50 exact field names' usefully reinforces the names param's maxItems and its exact-match requirement, but connection_context and the name pattern are left entirely to the 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?

States a specific verb (resolve) and resource (exact field names) and enumerates what comes back: versioned provider metadata, compatibility, enum values. This clearly distinguishes it from the query/analysis siblings. It stops short of naming a specific alternative, so it lands at 4 rather than 5.

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?

There is no explicit when-to-use statement and no named alternative. 'Queryability is not mutation eligibility' is a caution about interpreting results, not guidance about when to call this versus google_ads_query_preflight or google_ads_creation_capabilities_get. Usage must be inferred from the verb.

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