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 covered. The description adds genuine context beyond that by enumerating the metric families returned, including A/B variant results with leader and significance — content the agent otherwise could not anticipate since there is no output schema.

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 sentence, front-loaded with the resource and then the returned fields, with no filler. It is a noun phrase rather than a verb-led statement, which is slightly less directive, but nothing 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 one-parameter read tool with no output schema, the description covers the main thing the agent needs — what data comes back. It stops short of noting edge cases such as stats being unavailable before a send or whether figures are live versus final.

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% and the single 'id' parameter already documents that it accepts a campaign ID (cmp_xxx) or name. The description adds nothing about the identifier, but with full schema coverage the baseline of 3 is appropriate.

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 (a sent campaign) and enumerates exactly what is returned — delivery, opens, clicks, bounces, unsubscribes, mailbox providers, and A/B results. That makes the purpose unmistakable, though it never explicitly contrasts with get-campaign (configuration) or get-automation-stats, which are the nearest siblings.

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 statement of when to call this versus get-campaign, list-campaigns, or get-automation-stats, and no prerequisites such as 'the campaign must have been sent'. The agent must infer the usage context entirely from the tool name.

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