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

Annotations already declare the safety profile (not read-only, not destructive, not idempotent). The description goes beyond that by disclosing real behavioral effects: supplying daily_budget switches the campaign to CBO and removes separate ad-set budgets, and confirm=false produces a preview rather than a live creation. It doesn't discuss permissions or error modes, so 4 rather than 5.

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 purpose sentence is front-loaded and the rest is dense parameter documentation with no filler. The prose is packed into run-on clauses rather than cleanly separated points, which slightly hurts scannability but wastes no words.

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 an output schema present, return values need no explanation, and annotations cover the mutation safety profile. The description supplies the high-value omissions (objective enum, CBO behavior, preview flag, ad-category rules). Minor gaps remain, such as not mentioning the default PAUSED status, but overall 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?

Schema description coverage is 0%, so the description must carry the load, and it does for the non-obvious parameters: it enumerates the objective values (which the schema does not), explains daily_budget's currency units and CBO side effect, and defines the special_ad_categories format and when declaration is required. It leaves name/status/account_id unexplained, but those are self-evident.

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?

"Creates a Meta campaign" states a specific verb and resource, and the resource (campaign) is distinct from siblings like create_meta_adset or create_meta_carousel_ad. It does not, however, explicitly contrast itself against those siblings, so it lands at clear-but-undifferentiated rather than a 5.

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 explicit "use this when / use X instead" guidance. Usage is only implied through the parameter notes (e.g., preview via confirm=false, CBO triggered by daily_budget). An agent can infer context but is not told when to prefer preview mode or how this relates to create_meta_adset for the ad sets it references.

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