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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), but the description adds critical context beyond them: the 'WRITE — changes your live account' warning, the fact that the ad set is created PAUSED rather than live, and the confirm:true gate. An agent knows the blast radius and the required safety flag.

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?

Three compact clauses, with the highest-severity information (WRITE, live account) front-loaded in brackets and the confirm gate last. No sentence 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?

For a 13-parameter write tool with full schema coverage and annotations present, the description covers the essential behavioral facts an agent needs. The only gap is that, with no output schema, it does not indicate what is returned (e.g., the new ad set id) after creation.

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 100%, so every one of the 13 parameters is already documented in the schema (including enum for status and defaults for budget/age/targeting). The description only restates the areas covered and adds no format or syntax detail beyond the schema, so the baseline of 3 applies.

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 ('Create a Meta ad set under a campaign') plus the scope of what it configures (budget, optimization goal, country/age/gender targeting). This clearly distinguishes it from siblings like meta_ads_create_campaign and meta_ads_create_image_ad.

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?

The description conveys prerequisites ('Requires confirm:true') and the resulting state ('Created PAUSED'), which implies when it is safe to call. However, it never says when to choose this over meta_ads_create_campaign or meta_ads_boost_post, so alternative-selection guidance is absent.

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