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

Far beyond the annotations (destructive/openWorld/idempotent hints), it discloses the full enrol-gate eligibility rules, the skip-reason counting behavior, the approval_required two-call flow with the exact error payload shape, and that dashboard guardrails still apply. This is unusually rich behavioral disclosure for a mutation tool.

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?

Purpose and the enrol-gate mechanics are front-loaded, and most sentences carry distinct facts. It is a dense paragraph that could be broken up, but there is little outright waste.

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 supplies return-side context (counts explaining skips, the approval_required error object), the gating semantics, and scope limits, so an agent has everything needed to call it and interpret the result.

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 already 100%, so the baseline is 3; the description adds genuine value by explaining the approval_token retry flow that the schema only describes statically ('call again with the token'). It adds little about site_ids/campaign_id beyond what the schema already documents.

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 ('Add sites to a campaign') and anchors it to a familiar UI action ('Add to campaign on the Websites tab'). It is clearly distinguishable from the sibling add_creators_to_campaign, which targets a different entity type.

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?

Gives strong conditional context: draft campaigns only grow the audience while active/paused campaigns enrol immediately through the enrol gate, and creator-type campaigns refuse websites. It does not explicitly name an alternative tool or a when-not-to-use condition, which keeps it short of a 5.

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