SiteCheck

Check e-mail addresses without sending mail

email_check

Read-only

E-mail pre-check without SMTP: syntax, whether the domain can receive mail (MX or implicit MX, null MX, non-existent domain), disposable domain (9,000+ domain CC0 list), role account (info@, sales@...), free provider and a typo suggestion (gmial.com -> gmail.com). Verdict invalid / risky / unknown. Up to 50 addresses per call with emails=. Related tools on this server, for a different need: email_reply when you need to generate a reply to an e-mail for a chosen intent. Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "email_check"
  }
}

Input Schema

Name	Required	Description	Default
`email`	No	One e-mail address
`emails`	No	Alternative: up to 50 addresses, comma-separated

Output Schema

Name	Required	Description	Default
`mx`	No
`note`	No
`role`	No
`email`	No
`total`	No
`counts`	No
`domain`	No
`mxHosts`	No
`reasons`	No
`results`	No
`verdict`	No
`disposable`	No
`normalized`	No
`suggestion`	No
`freeProvider`	No
`disposableListSize`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 14, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "counts": {},
+    "disposable": {},
+    "disposableListSize": {},
+    "domain": {},
+    "email": {},
+    "freeProvider": {},
+    "mx": {},
+    "mxHosts": {},
+    "normalized": {},
+    "note": {},
+    "reasons": {},
+    "results": {},
+    "role": {},
+    "suggestion": {},
+    "total": {},
+    "verdict": {}
+  },
+  "type": "object"
+}

First observedOct 8, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare readOnlyHint and openWorldHint, and the description adds meaningful context beyond them: a per-call cost ($0.002 USDC via x402 on Base/Solana/Arc), that failed calls are not charged, and the batch cap of 50. It does not disclose rate limits, latency, or what 'unknown' means operationally, which keeps it from a 5.

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?

Core capability and the check list are front-loaded in one dense sentence, followed by verdict taxonomy, batch limit, sibling routing, and pricing. Every element is relevant, though the run-on check enumeration is harder to scan than a short bulleted list would be.

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?

With an output schema present, the description need not explain return shape, and it still summarizes the verdict taxonomy. For a two-parameter read-only tool it is nearly complete; the only gap is not clarifying precedence when both input parameters are provided.

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?

Schema coverage is 100% and both parameters are documented there, so the schema carries the load. The description only reinforces the 50-address cap and the 'emails=' alternative form, adding little syntax or precedence guidance (e.g., what happens if both email and emails are supplied). Baseline 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?

The description names a specific verb and resource ('E-mail pre-check without SMTP') and enumerates exactly what is checked: syntax, MX/implicit MX/null MX/non-existent domain, disposable domains, role accounts, free providers, typo suggestions, and the invalid/risky/unknown verdict. It also explicitly distinguishes itself from the sibling email_reply, so an agent can select it without opening either schema.

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?

It gives a clear condition for using the sibling instead ('email_reply when you need to generate a reply to an e-mail for a chosen intent'), which is real when-to-use routing. It does not state when this tool should NOT be used (e.g., deliverability verification vs. actual SMTP probing, or that it cannot confirm a mailbox exists), so it falls short of full exclusion guidance.

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

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