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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so safety is covered. The description adds real value beyond that by disclosing the breadth of the payload ('in one call', wide field list) which warns the agent this is a heavy single response rather than a narrow lookup. It omits any note on response size, latency, or pagination, keeping it from a 5.

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?

Front-loaded with 'Start here' and the payoff ('in one call'), then a single dense enumeration that earns its length by mapping the returned payload. The middle clause is a long run-on list that could be trimmed slightly, but nothing is filler.

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?

There is no output schema, so the description carries the burden of describing return values — it does so thoroughly, listing campaign fields, conversion actions, and setup problems. It doesn't clarify the response shape (sections vs flat) or handling when an account has no campaigns, a small remaining gap.

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?

Both parameters have 100% schema description coverage, including the manager-account nuance for login_customer_id, so the schema does the heavy lifting. The description adds no additional parameter meaning (e.g., what happens if login_customer_id is omitted when access is via a manager), so 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 ('understand how an account is set up, in one call') and then enumerates the exact resources returned: campaigns with status, type, dates, budget, bidding, 30-day spend/conversions, budget-lost impressions, negative keywords, and conversion actions. This is clearly distinguishable from siblings like campaign_performance (single-dimension) and run_gaql_query (explicitly says 'No GAQL needed').

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?

'Start here' gives explicit entry-point guidance for account onboarding/orientation, and 'No GAQL needed' implicitly steers agents away from run_gaql_query for this purpose. It does not explicitly say when to prefer campaign_performance or find_wasted_spend instead, so alternatives are only partially addressed.

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