BlackVeil DNS & Email Security Scanner

check_mx_reputation

Read-onlyIdempotent

Check whether the mail server (MX) IP addresses are listed on spam blocklists (Spamhaus, Barracuda, SORBS, and other RBLs). Also verifies reverse DNS for MX hosts. Use when you want to know if your mail server IP is blacklisted, or if your MX is on any blocklist — distinct from check_rbl which checks a specific IP directly.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "domain": "<domain>"
    },
    "name": "check_mx_reputation"
  }
}

Input Schema

Name	Required	Description
`domain`	Yes	Domain, e.g. example.com
`format`	No	Output verbosity.
`force_refresh`	No	Bypass the cache.

Output Schema

Name	Required	Description	Default
`score`	Yes
`passed`	Yes
`partial`	No
`category`	Yes
`findings`	Yes
`checkStatus`	No
`verdictWithheld`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedNov 12, 2026

changedInput schema / properties / domain / description

Previous value: -"Domain to check (e.g., example.com)"New value: +"Domain, e.g. example.com"

changedInput schema / properties / force_refresh / description

Previous value: -"Bypass cache and run a fresh check. Useful after DNS changes."New value: +"Bypass the cache."

changedInput schema / properties / format / description

Previous value: -"Output verbosity. Auto-detected if omitted."New value: +"Output verbosity."

Changed1 schema field changedOct 25, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
Changed1 schema field changedOct 5, 2026
- addedOutput schema / properties / verdictWithheld
```
Added value: +{
+  "type": "boolean"
+}
```
Changed2 schema fields changedAug 18, 2026
- addedOutput schema / properties / checkStatus
```
Added value: +{
+  "type": "string"
+}
```
- addedOutput schema / properties / partial
```
Added value: +{
+  "type": "boolean"
+}
```

Changed1 schema field changedJul 2, 2026

addedInput schema / properties / force_refresh

Added value: +{
+  "description": "Bypass cache and run a fresh check. Useful after DNS changes.",
+  "type": "boolean"
+}

Changed1 schema field changedMay 26, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": {},
+  "properties": {
+    "category": {
+      "type": "string"
+    },
+    "findings": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {},
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "passed": {
+      "type": "boolean"
+    },
+    "score": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "category",
+    "score",
+    "passed",
+    "findings"
+  ],
+  "type": "object"
+}

First observedApr 21, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds real value beyond them by disclosing the external services queried (Spamhaus, Barracuda, SORBS, other RBLs) and the extra reverse-DNS verification step. It does not mention caching behavior or the rate-limit/query-cost implications of hitting multiple public RBLs, which is the main remaining gap for an open-world 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?

Three sentences, front-loaded with the core action, and the sibling distinction comes last where it belongs. Minor redundancy between 'if your mail server IP is blacklisted' and 'if your MX is on any blocklist', which restate the same trigger in two forms.

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, return values need not be described, and annotations cover the safety profile; the description fills in scope (which blocklists, plus reverse DNS). It is close to complete, though it could have noted caching (implied by force_refresh) or behavior when a domain has no resolvable MX.

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 description coverage is 100% and all three parameters (domain, format, force_refresh) are documented inline, so the schema carries the burden. The description adds no parameter-level detail — notably it never clarifies that 'domain' is the domain whose MX records get resolved before its IPs are checked, which would have removed a real ambiguity. 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 states a specific verb and resource: check whether MX IP addresses appear on spam blocklists, naming concrete RBLs (Spamhaus, Barracuda, SORBS) and adding that reverse DNS for MX hosts is also verified. It explicitly distinguishes itself from the sibling check_rbl, which resolves ambiguity without the agent needing to open 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 Guidelines5/5

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

It gives an explicit trigger ('Use when you want to know if your mail server IP is blacklisted, or if your MX is on any blocklist') and names the alternative with its distinguishing condition ('distinct from check_rbl which checks a specific IP directly'). That is the when-to-use plus alternative routing an agent needs.

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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