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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the description goes beyond them by disclosing the response contents, the warm-up phase semantics, the perCampaign=false edge case (every campaign uses the org sender, not a chosen one), and the instruction to warn the user before scheduling a large campaign when unvalidated. That is real behavioral context an agent cannot get from annotations.

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?

The critical action and precondition are front-loaded in the first sentence, followed by a structured 'Returns:' enumeration. The sender/default explanation is dense but necessary; the field list is slightly long and the senders sub-field parenthetical is wordy, keeping it just short of top marks.

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?

There is no output schema, so the description must explain return values, and it does so field by field including validation status, warm-up state, rate cap, throttle, and per-sender selectability reasons. For a zero-parameter read tool with annotations covering safety, nothing an agent needs to call and interpret it correctly is missing.

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?

The tool takes zero parameters, so the schema baseline is 4. The description does not describe any input parameters, but it usefully explains how the returned identityId maps onto the sender_identity_id parameter of the sibling nevent_create_campaign, which adds cross-tool meaning beyond this tool's empty 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?

States a specific verb and resource ('verify the tenant is ready to send email') and enumerates exactly what the call returns: sender domains with validation status, warm-up phase, rate cap, throttle, and selectable senders. This clearly distinguishes it from sibling tools like nevent_get_suppressions_summary and nevent_get_campaign_deliverability.

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?

Opens with an explicit precondition ('Call this before creating a campaign'), tells the agent how to act on the result (pass a selectable identityId as sender_identity_id to nevent_create_campaign, omit to use the default), and names a complementary tool for a full deliverability check. The when-to-use, when-to-omit, and combine-with guidance are all present.

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