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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the description's burden is lighter. It adds the useful fact that results are aggregated by level/date range, but says nothing about row caps beyond 'limit', pagination behavior, or what happens when the account has no data.

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?

A single dense sentence that front-loads the returned metrics before the breakdown dimensions and window. No filler, though it is terse enough that an extra clause on aggregation/read-only reporting could have earned its place.

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 read-only reporting tool with no output schema, the description correctly enumerates the returned metrics and the available granularity, which is the key missing piece otherwise. It omits any indication of response shape (row objects, totals) but is adequate to call the tool 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 100% with defaults and a full enum for date_range documented inline, so the schema carries the semantics. The description adds no extra meaning for level, limit, date_range, or customer_id beyond what is already declared.

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 ('Get') plus the exact resource and metric set (impressions, clicks, cost, CTR, avg CPC, conversions) and the three supported breakdown levels. That makes the purpose unambiguous, but it never names or contrasts with siblings like google_ads_query or google_ads_get_campaign, so it falls short of a 5.

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?

Usage is only implied by the metric/breakdown framing; there is no explicit 'use this when you want aggregated performance reporting rather than raw rows or a single-entity lookup'. No when-not conditions or prerequisites (e.g. account connected) are stated.

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