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

Annotations already declare read-only, idempotent, non-destructive behavior, so repeating 'Read-only' adds little. But the description adds genuinely useful caveats beyond the annotations: 30-day retention, omission of Google Ads Editor changes and some Change History rows, and minute-level lag. These are the kind of source-data limitations an agent cannot get from schema or annotations.

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 core sentence is front-loaded and dense with useful specifics, and the caveats follow compactly. The trailing 'Tools revision: 5c9bea8f.' is build metadata that does not help an agent invoke the tool and could be dropped.

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?

An output schema exists, so return values need not be explained, and the description adequately covers the data source and its limitations. The gap is parameter coverage: with six parameters and 0% schema descriptions, omitting `detail`, `render`, `campaign_id`, and `max_findings` leaves meaningful invocation behavior undocumented.

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 must carry parameter meaning, yet it only documents `days` (1-30, default 7), which is genuinely helpful beyond the bare integer schema. The other five parameters — `detail` and `render` enums, `campaign_id` filtering, `max_findings`, and `customer_id` — are never mentioned, leaving the agent to guess their semantics.

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 a specific verb and resource ('List what changed in the account') and enumerates the exact dimensions returned (when, by which Google login, which channel). This clearly distinguishes it from siblings like account_health_score or full_audit, which analyze rather than enumerate changes.

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: an agent can infer this is the tool for auditing recent account changes, and the 30-day Google retention window signals a bounded lookback. However, there is no explicit when-to-use/when-not guidance or named alternative (e.g., versus full_audit or list_recommendations) to route an agent deciding between change tracking and diagnostics.

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