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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds real beyond-annotation context: which actions are immutable via API (google_managed imports) and the diagnostic fact that with no enabled primary action every campaign reports 0 conversions — a genuinely useful behavioral disclosure.

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-loads the returned fields, then layers the google_managed caveat and the 0-conversions warning. Dense but every clause earns its place; only marginally long for a list tool.

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 carries the return-value burden and does so by enumerating the fields returned, plus the critical zero-conversion caveat. For a read-only single-param list tool this is sufficient for correct invocation.

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% and the single parameter (customer_id) is never explained in the description — no format, source, or meaning is given. With below-50% coverage the description should compensate and it does not, even though the parameter name is fairly self-evident.

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 (list) and resource (conversion actions) for a given account, and then enumerates exactly which fields are returned (type, category, status, primary flag, counting, default value). This distinguishes it cleanly from the sibling mutators ads_create_conversion_action and ads_update_conversion_action.

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 description implies a read/audit context and usefully warns that google_managed actions cannot be changed via the API (change them in Google Ads), which steers behaviour. However it never explicitly names the alternative tools (ads_create_conversion_action / ads_update_conversion_action) or states when an agent should call this versus those, so usage is only implied.

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