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

With no annotations, the description discloses substantial behavior: the tool is a ledger-only read, scopes give server-side batching with separate pagination, continuation is bound to ledger generation and page size, and Meta min_as_of must not be sent. It does not discuss auth, rate limits, or detailed errors, but the main pagination and consistency contract is exposed.

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 the tool's identity and then gives a compact call contract without filler. It is dense and uses terms like 'trust coverage' and 'meta.next_continuation' without unpacking them, which slightly reduces readability.

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 15-parameter read tool with no output schema and no annotations, the description explains the required arguments and pagination behavior but omits response shape details and several optional parameter interactions. It is sufficient for a basic correct call but incomplete for advanced or edge-case usage.

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 7%, and the description compensates for the most important call contract (required params, scope/scopes exclusivity, continuation usage). However, page, fields, wait_ms, require_complete_range, consistency, response_mode, and date_range_mode are left to schema defaults and enums, leaving several optional parameters under-explained.

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 opens with 'Canonical compact ledger-only Insights read', naming a clear operation and resource and signaling it is the standard read path. It does not explicitly contrast with sibling insight tools like google_ads_insights_query_daily or google_ads_insights_overview_query, so differentiation is implied rather than stated.

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 directly instructs the caller to pass query_contract_version=1, group_by, explicit date_from/date_to, and exactly one of scope or scopes, and it explains when to use scopes versus a single scope. It does not state when not to use this tool in favor of an alternative sibling, so exclusions are absent.

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