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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds real context beyond them by explaining the authoring/approval workflow limitation and the passkey requirement. It does not mention pagination behavior despite a limit parameter, which keeps it from a 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?

Two tight sentences: the payload is front-loaded, then the critical API constraint. No filler, and every clause carries information the agent needs.

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 must convey return shape, and it does (campaign attributes plus a per-status count). It omits pagination behavior and the default ordering/size, which matters for a tool with a limit parameter.

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 75% and the schema documents app, status values, and environment default, so baseline is 3. The description adds only the framing that all results are scoped to one application and that status filtering produces the per-status count, without clarifying limit or status semantics beyond the schema.

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 names the resource (campaigns), the scope (one application), and the return payload (status, channel, audience, delivery statistics, plus a per-status count), which is well beyond the tautological title. It stops short of naming the closest sibling (get_campaign_stats), so the agent still has to infer the boundary between listing campaigns and fetching one campaign's stats.

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 second sentence gives a clear when-not condition: authoring and approval are impossible over this API path because they require a second operator and a fresh passkey. That prevents the agent from attempting a mutation via this listing tool. It does not, however, explicitly route to get_campaign_stats for single-campaign metrics.

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