Check a send without sending

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

The description openly states 'Sends nothing', aligning with the readOnly and idempotent annotations. It also explains what the tool does (reports whether email would go out) and what it does not do (send), providing full transparency about side effects.

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 description is extremely concise, using two short sentences to convey the tool's purpose, behavior, and recommended usage. There is no redundant or extraneous information.

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?

Given the tool's simplicity and the absence of an output schema, the description provides enough context for correct usage. It tells when to use it, what it does, and what it avoids, though it does not specify the exact return format or potential edge cases, which are less critical for a dry-run validation tool.

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 schema has no descriptions for any of the four parameters, and the tool description does not elaborate on how 'to', 'html', 'subject', or 'template_id' are used in the validation logic. Since schema description coverage is 0%, the description should compensate but does not mention any parameter details.

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 clearly states it is a dry run that reports whether the email would go out and names blockers, explicitly contrasting with actual sending. It distinguishes itself from sibling tools like vaemail_send_email and vaemail_diagnose_deliverability by focusing on validation without sending.

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 description gives explicit usage guidance: 'Use it right after setup, before the first real message.' This tells the agent exactly when to invoke this tool, and also implies when not to (for actual sending).

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