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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds valuable domain context beyond annotations by stating that budgets are in cents and that campaign_id scopes the listing to a campaign. It does not cover return format or pagination, but with annotations handling the safety profile, this is a meaningful addition.

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 description is two short sentences with zero waste. The main action is front-loaded, followed by the optional filter and a useful units note.

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?

Given a simple read-only tool with an output schema and comprehensive annotations, the description is largely sufficient. It could be more complete by mentioning the account_id requirement, but that gap is minor given the structured fields already present.

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 compensate. It explains the behavior of campaign_id ('limits to that campaign') but says nothing about the required account_id parameter. The budget-unit note is not tied to any parameter in the schema, leaving half the parameters undocumented.

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 states a specific verb ('Lists') and resource ('Meta ad sets'), and the conditional filter on campaign_id makes the scope clear. It is easily distinguishable from sibling tools like list_meta_ads or list_meta_campaigns by the resource it operates on.

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?

It provides an implied usage context by explaining that campaign_id limits results to a campaign, but it does not state when to use this tool versus alternatives such as list_meta_ads or list_meta_campaigns. No exclusions or prerequisites are given.

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