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

Annotations already declare readOnlyHint=true and destructiveHint=false, so 'read-only' largely restates structured data. The one genuinely additive piece is that the tool only 'suggests what to pause or fix' — it recommends but never mutates, which matters to an agent deciding whether a follow-up call is needed. Nothing is said about data freshness, scan cost, or how the thresholds are computed.

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?

Two sentences: the first front-loads the purpose and the concrete detection criteria, the second supplies the read-only/advisory posture. No filler, no restatement of the name or title.

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?

With no output schema, the description still conveys enough shape to act on — flagged ad sets/ads with supporting signals — and the schema fully covers inputs. It stops short of defining what 'very high' or 'high frequency' mean numerically or what sections the output contains, which would help an agent interpret the result without a second call.

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 all 7 parameters documented, including enum meanings and the 'optional when only one account is enabled' note. The description adds no additional parameter guidance, so the schema carries the full burden and the 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 and resource ('find money spent without results') and enumerates the exact detection signals: zero-result ad sets/ads with spend, cost per result far above account average, high frequency, and low CTR. This clearly separates it from generic reporting siblings like meta_performance or meta_insights_query, which return data rather than a diagnosis.

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 signals enumerated imply the usage context (diagnostic audit of wasted spend), and the closing clause clarifies the tool advises rather than acts. However, there is no explicit statement of when to reach for this versus meta_insights_query or meta_performance, and no when-not-to-use guidance (e.g. accounts with no conversion tracking).

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