google_ads_campaigns_diagnose

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

With no annotations, the description carries the full burden and does so: it declares the tool read-only, describes the return shape (ordered issue list with plain-language description plus remediation hint), and discloses the failure semantics that supporting reads return null rather than aborting the call. That partial-failure behavior is genuinely non-obvious and would otherwise cause an agent to misread a sparse response.

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?

Four sentences, each doing distinct work: purpose, return contents, degradation behavior, then usage routing. Everything is front-loaded and there is no filler or repetition of the tool name.

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?

No output schema or annotations exist, so the description must cover return values and safety itself, and it does both plus the partial-failure contract. Nothing an agent needs in order to call this correctly and interpret the result is missing.

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%, including the customer_id credential-fallback rule, so the schema already supplies all parameter meaning. The description adds no parameter-level detail beyond it, which is the baseline 3 case.

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: explains why a campaign is not serving or under-delivering. It enumerates the exact status fields consumed (serving_status, primary_status, primary_status_reasons) and sample reason codes, so an agent can tell it apart from performance-report siblings without opening the schema.

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?

Explicitly says to use it before pulling raw performance reports and that it narrows the problem space, which is real routing guidance. It does not name the adjacent diagnostic siblings (analysis_delivery_collapse_diagnose, google_ads_health_check_all, google_ads_keywords_diagnose) or state exclusions, so it stops short of a 5.

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