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

Goes well past the annotations by disclosing the confirmation protocol: the first call mutates nothing and returns a question plus a confirmToken, and the second call needs identical arguments plus that token. It also states the send is a snapshot of the campaign as currently saved and that the subject is altered, neither of which the schema or annotations convey. Consistent with destructiveHint=true and openWorldHint=true.

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 compact paragraphs, purpose first and the confirmation mechanics second, so the agent reads the risky part before acting. A little wordy in the confirmation paragraph but no sentence is filler.

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?

No output schema, yet the description covers the return contract for the confirmation path (a question plus confirmToken) and the failure mode of calling without a token. For a destructive, non-idempotent send tool with five params, this is everything an agent needs to call it safely.

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 100%, so the baseline is 3, but the description adds real meaning: broadcastId originates from draftCampaign, `to` should be the person's own addresses, and confirmToken must never be invented or sent unconfirmed. That cross-tool provenance and the confirmToken guard are not in the schema text.

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 (send one test copy of a campaign) plus concrete scope: up to five addresses, from the workspace's verified domain, subject prefixed with [Test]. This clearly separates it from resendCampaign and scheduleCampaign, which act on real recipients.

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?

"For the person to check it in an inbox before it goes out, never for real recipients" gives an explicit when and when-not, and it points at draftCampaign as the source of broadcastId. It stops short of naming the closest sibling (previewSend) or explaining how this differs from a preview, so it is strong but not exhaustive.

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