verify_bulkValidate up to 10 email addresses at once using DNS checks, returning per-email results and a summary.
Batch verification of up to 10 emails. Same DNS-based checks as check_email. Returns a per-email array plus a summary.
| Name | Required | Description | Default |
|---|---|---|---|
| smtp | No | Opt-in SMTP handshake for all emails. | |
| emails | Yes | 1–10 email addresses |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses the check type ('Same DNS-based checks as check_email') and the return shape ('per-email array plus a summary'), which is useful, but it omits the SMTP opt-in behavior that the schema documents and says nothing about authentication or rate limits.
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?
Three short sentences with no filler, and the batch scope is front-loaded. It is appropriately sized for a simple bulk verification tool, though it could be slightly tighter by not repeating the 'up to 10 emails' limit already in the title.
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 low-complexity read tool with no output schema and no annotations, the description gives the return format and the nature of the checks. However, it leaves gaps around the smtp option's implications and when to prefer this over single-email verification, so it is adequate rather than complete.
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%, so the schema already documents both the 1–10 email array and the opt-in smtp flag. The description adds no parameter-level detail beyond the batch size already stated in the schema, so the baseline 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 states a specific verb and resource: batch verification of up to 10 emails. It also relates itself to the sibling check_email by noting 'Same DNS-based checks,' which helps an agent understand what it does, though it stops short of fully routing between bulk and single-email usage.
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 phrase 'Batch verification of up to 10 emails' implies the tool is for multiple addresses, but there is no explicit when-to-use guidance versus check_email for a single address or versus check_mx/is_disposable. Usage is left to inference from the batch framing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.