BlackVeil DNS & Email Security Scanner

check_rbl

Read-onlyIdempotent

Check MX server IP reputation against 6 DNS-based Real-time Blocklists (SpamCop, UCEProtect, Mailspike, Barracuda, PSBL). Resolves MX hosts to IPs first.

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_rbl"
  }
}

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

B3.2/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: it performs MX resolution before querying and names the external blocklist providers being contacted. It omits cache behavior (despite a force_refresh param) and any cost/latency or rate-limit implications of hitting six third-party DNSBLs.

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?

Two sentences, front-loaded with the core action, zero filler. The only flaw is the internal inconsistency between '6' and the five enumerated blocklists, which wastes a small amount of agent attention.

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

Completeness3/5

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

An output schema exists, so return values need not be explained, and annotations cover the safety profile. Still, the 6-vs-5 mismatch leaves ambiguity about which blocklists are actually queried, and nothing tells the agent what happens when a domain has no MX records recorded or whether results are cached.

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%, so all three parameters are already documented in the schema; baseline 3 applies. The description only clarifies that the domain parameter drives MX-host resolution, and says nothing about 'format' verbosity or what 'force_refresh' bypasses.

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

Purpose4/5

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

States a specific verb and resource ('Check MX server IP reputation') plus the mechanism (6 DNS-based RBLs) and an internal step ('Resolves MX hosts to IPs first'). It is clearly distinguishable from neighbors like check_mx or check_dnssec, though it never names a sibling it might be confused with (e.g., check_mx_reputation). Minor defect: it claims '6' blocklists but lists only five names.

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

Usage Guidelines2/5

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

No when-to-use or when-not-to-use guidance at all. With siblings such as check_mx_reputation, check_realtime_threat_feed, and check_dbl present, an agent gets no help deciding which reputation check to run, and no prerequisites (does the domain need existing MX records?) are stated.

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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