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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the closing 'read-only: nothing is ever changed in Meta' adds modest assurance rather than new information. The genuinely additive disclosure is the unit contract — amounts in hundredths of the ad account's currency, rates as fractions — which prevents a costly misinterpretation of every returned number. No mention of auth needs, rate limits or response size, but the unit semantics are the higher-value disclosure here.

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?

Structure is strong: the content inventory comes first, then the units contract, then the safety note — three distinct concerns in three sentences with no filler. The first sentence is long and list-dense, but every item in it is a returned field an agent would otherwise have to guess at, so nothing is wasted.

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 correctly carries the burden of describing returns, and it does so thoroughly, including units and both series granularities. The main omission is coverage of the 'range' parameter's launch/today/yesterday/7/30 options in prose, and any hint of response shape or volume for a tool that returns daily and hourly series plus budgets.

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 100%, so the baseline is 3; the description earns above that by explaining what the 'hours' window means semantically — each window is compared against the same span before and since launch — which is reasoning the enum description does not spell out. It does not mention 'range' values (today, yesterday, 7/30 days), 'source' selection or 'environment', but those are fully documented in the schema.

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?

Names a specific resource (Meta Ads account) and enumerates exactly what the overview contains: spend, impressions, reach, link clicks, landing page views, results/cost per result, hourly and daily series, budgets with pacing and learning phase, and the issues list. An agent can distinguish this consolidated overview from narrower siblings such as get_meta_ads_breakdowns, get_campaign_stats or list_meta_ads_issues without opening any 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?

Usage is implied by the content inventory — you can infer this is the headline dashboard tool — but there is no explicit when-to-use or when-not-to-use guidance relative to get_meta_ads_breakdowns, get_metric_series, get_analytics_overview or list_meta_ads_issues. The gap is most visible around the issues list, which is offered here yet also has a dedicated sibling, with no rule for choosing between them.

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