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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely useful behavioral context — amounts are in whole currency units, and payment method may be null when Meta withholds it — but says nothing about auth requirements, pagination, or error behavior.

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 tight sentences with no filler; the primary purpose leads and the units/nullability caveats follow. Every clause carries information an agent can act on.

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 does well to enumerate the returned fields, their units, and the null case. However, it leaves the required adAccountId parameter entirely unexplained and gives no hint about failure modes when the id is malformed or the connection lacks permission.

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?

The description mentions no parameter at all, including the required adAccountId, whose 'act_\d+' format never appears outside the schema pattern. With schema coverage at only 67%, the description should have compensated for the unlabeled pattern parameter, and it does not.

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 ('Return one ad account') and enumerates the payload fields it returns (status, amount spent, spending limit, payment method on file). 'One ad account' implicitly separates it from ads_list_accounts, but no sibling is named, so the differentiation is inferred rather than explicit.

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?

There is no when-to-use statement, no prerequisite, and no routing to an alternative such as ads_list_accounts or ads_get_insights. The only contextual note is about the null payment-method case, which is a return-value caveat rather than usage guidance.

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