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

Annotations already declare readOnlyHint=true, destructiveHint=false and a closed-world scope, so the safety profile is covered. The description adds a genuinely useful trait the annotations do not: pagination defaults to 20 rows while summary/total span the full filtered scope, which tells an agent the aggregate is not page-limited. It still leaves 'ledger-backed', the cached consistency default, and the meaning of 'one scope' unexplained.

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 with no filler, and the pagination/summary caveat comes after the scoping statement. It is efficient, though the opening jargon phrase costs clarity without earning space.

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 17-parameter, zero-required, no-output-schema analytics query, the description omits scope definition, required context (customer_id, connection_context), and the distinction between grouped and daily view modes. What is present is accurate but far short of what an agent needs to invoke this 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 only 6% across 17 parameters, and the description adds almost no parameter semantics beyond restating the 20-row page_size default. Critical inputs like customer_id, connection_context, group_by, view_mode, window_days and require_complete_range are left entirely to the schema, so the low coverage is not compensated.

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 names the resource ('insights overview') and implies a read query, but 'Ledger-backed' is unexplained jargon and 'for one scope' is vague without saying what a scope is. It does not distinguish this tool from close siblings such as google_ads_insights_query_daily, google_ads_insights_overview_batch, or insights_query_consistent, so an agent cannot tell which overview/query variant applies.

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?

No when-to-use, when-not-to-use, or alternative guidance is given despite a crowded sibling set of insights/query tools. The only conditional statement is about default row counts, which is behavioral rather than routing guidance.

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