Email Verifier MCP Server

Verify email addresses on your own verification key

verify_emails

Read-only

Checks up to 5,000 email addresses for deliverability with your ZeroBounce, NeverBounce, MillionVerifier, BounceBan, or Reoon account, returning verdicts and flags for each address.

Instructions

Check whether email addresses will deliver, using the caller's own ZeroBounce, NeverBounce, MillionVerifier, BounceBan, or Reoon account. Give emails (1 to 5,000 addresses) and provider (zerobounce by default). The service API key is read from this server's environment (EMAIL_VERIFIER_API_KEY), never from the tool arguments, and the service bills each check to the key owner. Returns one flat row per address: verdict (valid, invalid, catch_all, risky, or unknown), provider_status, provider_sub_status, is_role, is_free_email, is_disposable, did_you_mean, row_status, and error_reason. Addresses with broken syntax are not sent; repeats are checked once. If the key is missing the call is refused before any run starts. Bad input returns one free row whose error_reason starts with input_invalid. A run that does not succeed is returned as an error with its run ID. Read-only; requires an APIFY_TOKEN; Apify charges per address the service answered valid, invalid, catch all, or risky.

Input Schema

Name	Required	Description
`email`	No	One more address, added to emails.
`emails`	Yes	The addresses to verify, 1 to 5,000 per run. A repeat of an address is verified and charged once.
`provider`	No	The service the key in EMAIL_VERIFIER_API_KEY belongs to: zerobounce, neverbounce, millionverifier, bounceban, or reoon. Default zerobounce.
`concurrency`	No	How many addresses are checked at the same time, 1 to 20. Default 5. Lower it if the service plan has a tight rate limit.
`max_charge_usd`	No	Optional. The run stops before an actor charge that would pass this amount. The verification service bills separately.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Nov 1, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Goes well past the annotations: discloses who is billed (the key owner, per answered address, plus Apify charges), that broken-syntax addresses are skipped and repeats checked once, that a missing key refuses the call before any run, that bad input returns one free row with an input_invalid error_reason, and that failed runs return an error with a run ID. That is unusually complete operational context for a read-only tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose, then input shape, then billing/security, then return fields, then failure modes — a sensible ordering with dense, non-repetitive sentences. Slightly long as a single paragraph and 'Read-only' restates the annotation, but nothing is filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite having no output schema, the description enumerates the returned row fields and the two error shapes (free input_invalid row vs. error with run ID), and it covers billing, auth prerequisites, and dedupe. An agent has everything needed to call it and interpret the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

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 semantics the schema does not: the API key is never a tool argument, repeats are billed once, and malformed addresses never reach the provider. These details directly affect how an agent should shape its input.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Check whether email addresses will deliver') plus the exact mechanism: the caller's own ZeroBounce/NeverBounce/MillionVerifier/BounceBan/Reoon account. An agent knows precisely what the tool does and whose account is used, with no sibling tools to confuse it with.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete invocation context: pass 1 to 5,000 addresses, provider defaults to zerobounce, and the API key comes from the server environment rather than arguments. It also states prerequisites (APIFY_TOKEN, EMAIL_VERIFIER_API_KEY) and what happens if the key is missing. No alternatives exist to route against, so no exclusions are needed.

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

Deploy Server

Other Tools

verify_emailsA