BlackVeil DNS & Email Security Scanner

check_dane

Read-onlyIdempotent

Check DANE/TLSA certificate pinning for SMTP at port 25. Resolves the domain's MX hosts and looks up TLSA records at _25._tcp., validating their syntax, usage/selector/matching-type fields and DNSSEC backing on the MX host's zone. The record is reported as present but UNVERIFIED: there is no certificate probe for port 25/SMTP, so the pinned data is never compared against the certificate the mail server actually serves (the comparable capture-and-compare pipeline exists only for check_dane_https at port 443, and is itself currently kill-switched there — see that tool's description). Use when asked if SMTP mail servers publish DANE/TLSA pinning; this does not confirm the pin matches the live certificate. For HTTPS DANE at port 443, use check_dane_https instead. Part of the scan_domain audit.

Input Schema

Name	Required	Description
`domain`	Yes	Domain to check (e.g., example.com)
`format`	No	Output verbosity. Auto-detected if omitted.
`force_refresh`	No	Bypass cache and run a fresh check. Useful after DNS changes.

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.

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

A4.6/5.0

Behavior5/5

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

Annotations already declare readOnly/idempotent/openWorld, so the description focuses on what annotations cannot convey: the record is reported 'present but UNVERIFIED' because there is no port-25 certificate probe, and the comparable pipeline in check_dane_https is itself kill-switched. This prevents an agent from over-claiming a passing pin.

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-loads the verb, target and port, then the mechanism, then the caveat and the alternative. Dense but every clause carries signal, though the nested aside about check_dane_https's kill-switch is slightly bulky for this tool's own definition.

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?

An output schema exists, so return values need not be explained. For a read-only DNS-analysis tool, the description covers scope, validation depth, the key limitation, and routing to the sibling — nothing needed to call or interpret it correctly is missing.

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%, so domain, format and force_refresh are already fully documented. The description adds essentially no parameter-level detail beyond implying the domain is the target; 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?

States a specific verb and resource with protocol and port: 'Check DANE/TLSA certificate pinning for SMTP at port 25', then spells out the mechanism (MX resolution, _25._tcp.<mx-host> TLSA lookup, field/DNSSEC validation). It is immediately distinguishable from check_dane_https, which is named explicitly.

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?

Gives an explicit trigger ('Use when asked if SMTP mail servers publish DANE/TLSA pinning'), an explicit exclusion ('this does not confirm the pin matches the live certificate'), and the alternative ('For HTTPS DANE at port 443, use check_dane_https instead'). Also notes its role in the scan_domain audit.

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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