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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety and idempotency profile is covered. The description adds only the instruction to name the date range in the answer, but says nothing about the row `limit`, result-size behavior, or query failure modes.

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 short sentences plus one instruction, with the core action front-loaded. The trailing 'Always name the date range in your answer' is an answer-formatting directive rather than tool behavior, so it is slightly out of place but still short and useful.

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 3-parameter, no-output-schema tool, the description covers purpose and use cases but omits the `limit` parameter's meaning and any sense of the returned row shape. Combined with rich annotations the gaps are modest, but an agent must still infer result-sizing behavior.

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 67% — `query` and `customer_id` are documented inline (including a GAQL example and the ads_list_accounts provenance), while `limit` is undocumented but constrained by default/min/max. The description adds no parameter detail beyond noting date ranges are relevant, so the baseline 3 applies.

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 and resource — 'Run a GAQL query against one Google Ads account' — which cleanly distinguishes it from siblings like ads_list_accounts (enumeration) and ga4_report (different platform). The mention of GAQL and Google Ads removes ambiguity about which report tool this is.

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?

Names concrete use cases (spend, clicks, conversions, cost per conversion, search terms, keyword performance), which tells the agent when this tool is appropriate. However, it offers no exclusions or pointers to alternative siblings (e.g. ads_keyword_ideas, ga4_report) for related-but-different analyses.

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