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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral value beyond that: budgets are returned in both minor units and *_major, and it instructs the agent to quote the major figure. It does not cover pagination or auth, but the currency-formatting note is a meaningful 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?

Two sentences, front-loaded with the purpose, followed by a concise caveat about budget units. No filler; every sentence earns its place.

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?

For a simple list tool with no output schema, the description usefully names the returned fields and explains the budget-unit convention. The remaining gap is the undocumented ad_account_id format, but otherwise it is complete enough to call correctly.

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?

There is one required parameter (ad_account_id) with 0% schema description coverage, so the description carries the burden but only implies account context via 'in a Meta ad account'. It does not document the parameter or the Meta account-id format (e.g. the act_ prefix), leaving the agent without format guidance.

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), resource (campaigns), scope (in a Meta ad account) and the fields returned (status, objective, budget). The read/list action is clearly distinguishable from the write-oriented siblings like meta_create_campaign, meta_set_campaign_budget and meta_set_campaign_status.

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 only implied by the 'List campaigns' wording; there is no explicit when-to-use guidance and no routing to alternatives such as meta_insights or meta_list_accounts. An agent can infer it fetches campaigns, but nothing states conditions or exclusions.

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