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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds only that the payload includes engagement/delivery rates; it omits any note on time window, refresh cadence, or behavior for campaigns with no sends.

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?

One front-loaded sentence naming the action and the returned metrics with no filler. It is appropriately short for a simple read tool, though the trailing metric list is somewhat enumerative rather than informative.

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 usefully sketches the returned metrics, and annotations cover the safety profile. It is nearly complete for a single-param stats getter, missing only time-range/scope semantics of the returned numbers.

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% for both params, so campaignId and apiKey are already documented in the schema. The description adds no format or sourcing detail beyond that, so the baseline 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 (get) and resource (stats for a specific campaign) and enumerates the metrics returned (open, click, bounce, delivery). It implicitly separates itself from get_automation_stats and get_workspace_usage via the 'campaign' resource, but never explicitly names the sibling it is not.

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?

No guidance on when to call this versus list_campaigns, get_automation_stats, or get_deliverability_status, and no mention of prerequisites such as the campaign needing to exist or already have sent mail.

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