A
licenseA
qualityB
maintenanceEnables real-time email verification via MCP tools, checking syntax, MX, disposable domains, and optional SMTP probe to determine deliverability with a VALID/RISKY/INVALID verdict.
2
8 npm
MIT
kluno-verify-mcp
by Kuldip99123
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@kluno-verify-mcpcheck if sarah@acme.com is a deliverable email"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
kluno-verify-mcp
MCP server for Kluno email verification. Connect Kluno to Claude Code, Claude Desktop, or any MCP-compatible client, and verify email addresses directly from your agent.
Setup
Get your API key from your Kluno dashboard at kluno.xyz.
Add this to your MCP client config:
Claude Code (.mcp.json)
{
"mcpServers": {
"kluno": {
"command": "npx",
"args": ["-y", "kluno-verify-mcp"],
"env": {
"KLUNO_API_KEY": "your-api-key-here"
}
}
}
}Claude Desktop (claude_desktop_config.json)
{
"mcpServers": {
"kluno": {
"command": "npx",
"args": ["-y", "kluno-verify-mcp"],
"env": {
"KLUNO_API_KEY": "your-api-key-here"
}
}
}
}Restart your client after adding this. Kluno will show up as a connected tool.
Related MCP server: InboxValid MCP Server
Tools
verify_email
Verifies whether an email address is deliverable.
Input: email (string, required)
Returns: the same JSON your dashboard/API returns — status (valid / invalid / catch-all / unknown), sub_status, reason, confidence, confidence_band, and metadata like mx_found / smtp_provider.
Kluno never guesses a fake "valid" — unknown is a real, honest answer when the mailbox truly can't be confirmed (e.g. behind a security gateway), not a cop-out.
Configuration
Env var | Required | Description |
| Yes | Your Kluno API key, from your dashboard at kluno.xyz. |
| No | Overrides the API base URL (defaults to |
Local development
npm install
KLUNO_API_KEY=your-key node index.jsThe server communicates over stdio, so it's meant to be launched by an MCP client, not run standalone in a terminal.
Available Tools
1 toolverify_emailA
Verify whether an email address is deliverable using Kluno. Returns an honest status (valid / invalid / catch-all / unknown) — Kluno never guesses a fake "valid" the way some verifiers do, so "unknown" is a real, meaningful answer (e.g. the mailbox sits behind a security gateway or the mail server would not give a clear answer).
ParametersJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| Yes | The email address to verify, e.g. jane@company.com |
TDQS
A3.9/5.0
Behavior4/5
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and does add real value: it discloses that the tool never fabricates a 'valid' result and that 'unknown' is a genuine outcome with concrete causes (security gateway, uncooperative mail server). It omits operational traits such as latency, cost, or rate limits, which matter for a live SMTP-style check.
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?
Purpose is front-loaded in the first clause and the elaboration follows. The sentence is somewhat long and the parenthetical explanation of 'unknown' borders on redundant with the preceding clause, but every element is relevant.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Completeness4/5
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter lookup with no output schema, the description appropriately explains the meaning of the returned statuses, which is exactly what the missing output schema would otherwise carry. It leaves out operational details like cost or speed, but nothing needed to call it correctly is absent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Parameters3/5
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
There is a single parameter with 100% schema description coverage, including an example format, so the schema does the work. The description adds no format or syntax detail beyond it, so the baseline of 3 applies.
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: 'Verify whether an email address is deliverable using Kluno.' An agent immediately knows the operation and the outcome types (valid / invalid / catch-all / unknown) without opening the schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Usage Guidelines3/5
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives context for interpreting results (what 'unknown' means, why it is honest) but never states when to call this tool, e.g. before a send or list-import, nor any preconditions. Usage is implied rather than directed, and there are no sibling tools to route against.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
1 tool update
v1.0.0- First observed
verify_email
TDQS
A4.1/5.0
Scored across 1 tool
Disambiguation5/5
There is only one tool, so there is no possibility of confusing it with another operation. Its purpose is clear and distinct.
Naming Consistency5/5
The single tool name `verify_email` follows a clear verb_noun snake_case convention. No inconsistent naming exists to compare against.
Tool Count4/5
A single-purpose email verification server can reasonably expose one focused tool. The count is minimal but not mismatched to the domain, though it offers no room for related operations like batch verification.
Completeness4/5
The tool covers the core verification operation and returns a rich status taxonomy including `valid`, `invalid`, `catch-all`, and `unknown`. Minor possible gaps such as bulk verification or historical results are not strictly required for the stated purpose.
Related MCP Connectors
Email validation for Claude and any MCP client — verdicts with evidence, bulk jobs, refunds.
Verify emails and domains for routing, disposable providers, role accounts, and SMTP risk.
Verify emails — deliverability, disposable/role/free detection, MX validity, domain age.
Emailable MCP — wraps the Emailable email verification API (emailable.com)
Related MCP Servers
- FlicenseNot gradedqualityCmaintenanceProvides email verification as an MCP tool, checking format, disposable domains, and mail server availability with structured results.-
- FlicenseNot gradedqualityCmaintenanceMCP server that exposes an email verification tool, returning verdicts of valid, invalid, or risky with reasons.-
- FlicenseNot gradedqualityBmaintenanceEnables AI agents to verify email addresses in real-time, checking syntax, DNS, MX records, and SMTP handshake, returning verdicts and deliverability scores without sending actual emails.-