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

Annotations already declare read-only, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds the returned field set, which is real value, but says nothing about pagination, result limits, or permissions on the account-scope path. Adequate rather than rich.

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 front-loaded sentence with the scope qualification and the returned fields; no filler, nothing trailing that adds no information.

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, listing the returned fields is exactly the compensating detail an agent needs to decide whether to call this or meta_insights. Remaining gaps are pagination behavior and how to obtain campaign_id/ad_account_id, which are minor for a read-only list tool.

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 coverage is 50%, and the one described parameter (ad_account_id) is already explained in the schema itself. The description's '(or a whole ad account)' reinforces the campaign-vs-account exclusivity, but campaign_id gets no semantics (format, prefix like act_/ID source) in either place.

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 ('List the ad sets') and enumerates the fields returned (status, budget, goal, locations, ages), which distinguishes it from meta_list_ads and meta_list_campaigns by resource type. It does not name siblings explicitly, 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?

The parenthetical '(or a whole ad account)' communicates the two scoping modes an agent can choose between, which is useful implied guidance. There is no explicit when-to-use/when-not or reference to alternatives such as meta_list_campaigns or meta_insights.

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