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

Annotations only declare readOnly=false, destructive=false, openWorld=true - a generic write profile. The description adds genuinely new behavior: campaigns land PAUSED (so nothing goes live unexpectedly), dry_run is a no-side-effect validation path, and budget is optional/CBO. It omits permission requirements and what the response contains, but the added context is substantive.

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?

Four short sentences, no filler, and the core action plus the PAUSED default are front-loaded. The 'Advantage campaign budget' parenthetical and the category example are slightly compressed but still readable.

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 10-parameter mutation with no output schema, the description covers the highest-risk behaviors (PAUSED default, dry_run) but leaves gaps on bid strategy, budget exclusivity, and account/folder defaults that an agent needs to construct a correct call.

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 40%, so the description must compensate and does so only partially: it explains dry_run, the campaign-level budget (CBO) and the purpose of special_ad_categories for regulated verticals. It leaves bid_strategy, lifetime_budget vs daily_budget, objective enum meanings, and account/folder resolution undocumented in both places.

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 opens with a precise verb+resource ('Create a campaign') and names Meta-specific mechanics (Advantage campaign budget, special_ad_categories, dry_run). It is clearly a Meta campaign creation tool as distinct from meta_create_adset or meta_create_ad, though the description itself never points to those siblings by name.

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 tells the agent two valuable things - the campaign is always created PAUSED, and dry_run validates without creating - which implicitly guides safe use. It does not say when to choose this tool over meta_create_adset/ad, or what sequence to follow afterward, so the when-to-use guidance is only implied.

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