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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about the default date window and the id-or-uuid filter convention, but it does not explain the return shape or whether results are grouped/paginated.

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 a single compact sentence with the core purpose front-loaded, and every clause carries information. The nested parentheticals make it slightly dense but not wasteful.

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 10 optional parameters, 0% schema description coverage, and no output schema, the description is only partially complete. It covers the date default and id/uuid filter convention, but omits campaign_key semantics and does not describe the returned totals beyond saying they are per provider.

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 0%, so the description has to carry parameter semantics. It compensates partially by explaining that website, account, and customer filters take an id or a uuid, and by specifying YYYY-MM-DD with a last-30-days default for the date range, but it leaves campaign_key and provider semantics under-specified.

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 resource and scope: ad spend/result totals for a date range, plus the same totals per provider. It is clear enough to distinguish this as a summary aggregation tool, but it does not explicitly contrast itself with sibling tools such as ads_insights_campaigns, ads_insights_timeseries, or ads_insights_websites.

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 description gives contextual details like the default last-30-days range, but it does not state when to use this tool versus the other ads_insights_* siblings or when not to use it. There is no explicit routing guidance.

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