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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real context beyond that: 'ledger-backed' implies authoritative server-side totals and 'server summaries instead of summing visible rows' warns that visible rows may be a page subset, which is non-obvious pagination semantics.

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, the scope limit front-loaded and the results-handling caveat second. No filler; each sentence carries distinct 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?

For a tool with a nested scopes array of 17 optional fields, zero schema descriptions, and no output schema, the description is too thin. It never explains what an 'insights overview' returns or how scopes are combined, leaving the agent to guess at both input semantics and result shape.

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 effectively 0% (only customer_id is annotated), so the description is expected to compensate. It adds only the 'up to 20 scopes' count, which the schema's maxItems already encodes, and explains nothing about the ~17 scope sub-fields (view_mode, consistency, window_days, query_contract_version) or connection_context.

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 resource ('insights overview') and a scope-batch limit ('up to 20 scopes'), so the agent knows it is a bulk read. But the verb is nominal ('overview') and it never distinguishes itself from close siblings like google_ads_insights_overview_query or google_ads_insights_query_daily, leaving ambiguity about which one to pick.

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 only guidance is 'Use server summaries instead of summing visible rows,' which tells the agent how to interpret results, not when to call this tool versus the sibling overview/query tools. No context, prerequisites, or alternatives are named.

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