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

Annotations already declare this read-only, open-world, idempotent, and non-destructive, so the safety profile is covered. The description adds useful behavior beyond that: results are JSON and capped at the first 500 rows, and it clarifies that GAQL restrictions apply. It does not explain error handling or how to retrieve rows beyond the first 500.

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 description is front-loaded with purpose, return format, and row limit, then moves to routing guidance and syntax constraints. Each sentence adds distinct value, and there is no redundant restatement of the name or schema.

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 complex, open-ended query tool with no output schema and 100% parameter coverage, the description covers the important return behavior, truncation, account scope, and GAQL constraints. It is nearly complete, though it does not describe error behavior or whether full results beyond 500 rows can be obtained.

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 100%, so all three parameters are already documented, including customer_id and login_customer_id. The description still adds meaningful semantics for the query parameter by explaining GAQL syntax limits and field-name caution, though it does not elaborate on the login_customer_id behavior beyond 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?

The description states a specific verb and resource: it runs a read-only GAQL SELECT on one account and returns rows as JSON. It also distinguishes itself from siblings by saying it is only for data the other tools do not cover, naming wasted spend, search terms, and campaign results as examples answered elsewhere.

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 explicit when-to-use and when-not-to-use guidance: only for data other tools do not cover, with concrete examples of sibling-covered cases. It also adds practical query guidance about AND-only WHERE clauses, using IN instead of OR, and avoiding guessed field names.

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