google_ads_query

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the description's 'read-only' framing is largely redundant. It does add real value with the note that costs are in micros and must be divided by 1,000,000 – a behavioral fact not in the annotations. It says nothing about pagination or how the 'limit' interacts with results, so it stops short of a 4.

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?

The purpose is stated in the first sentence, followed by one example and one unit caveat – no filler. The example spans several lines but earns its place by demonstrating the required query dialect.

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?

An output schema exists, so return values need not be described, and annotations cover the safety profile. However, for a tool with 0% schema description coverage and two required identifiers including the MCC login header, the description leaves an agent without enough to fill arguments correctly.

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% across four parameters, so the description must carry the burden and it does not. The example illustrates the shape of 'gaql' only; 'customer_id', 'login_customer_id' (a notoriously error-prone MCC-manager field) and 'limit' are entirely unexplained in both schema and description.

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 states a specific verb and resource (run a read-only GAQL query) and scopes it as unrestricted ('any'), which is genuinely distinct from the operation-specific siblings like google_ads_campaign_performance or google_ads_set_campaign_budget. It does not, however, explicitly say when this generic tool is preferred over those specialized tools, leaving the boundary to inference.

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?

The example query implies how the tool is used (select fields, from a resource, with a date segment filter), which is useful implied guidance. But there is no statement of when to reach for this versus the several google_ads_* siblings, no exclusions, and no prerequisites such as needing a customer account context.

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