BlackVeil DNS & Email Security Scanner

check_fast_flux

Read-onlyIdempotent

Detect fast-flux DNS behavior: performs multiple rounds of A/AAAA queries and checks whether IP addresses are rotating rapidly on each DNS query (a sign of botnet or malicious infrastructure). Compares IP answer sets and TTLs across rounds to identify rapidly rotating infrastructure used to hide malicious activity.

Input Schema

TableJSON Schema

Name	Required	Description
`domain`	Yes	Domain to check (e.g., example.com)
`format`	No	Output verbosity. Auto-detected if omitted.
`rounds`	No	Number of query rounds (3-5, default 3).
`force_refresh`	No	Bypass cache and run a fresh check. Useful after DNS changes.

Output Schema

TableJSON 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 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

A3.9/5.0

Behavior4/5

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

Annotations already declare the safe read-only, idempotent, non-destructive profile, and the description adds real behavioral context: it discloses the multi-round query method and that IP answer sets and TTLs are compared across rounds. It does not mention latency or cost implied by multiple query rounds, but it clearly exceeds what the annotations convey.

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 operation and its purpose, with no filler. Slightly redundant in restating 'rapidly rotating infrastructure' at the end, but efficient overall.

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 full schema coverage, an output schema handling return values, and annotations covering the safety profile, the description covers everything needed to invoke the tool correctly. Only the absence of when-to-use routing keeps it from being fully complete.

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, rounds, and force_refresh are all documented in the schema itself. The description adds no syntax or default detail beyond the schema, so the 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 (Detect) and resource (fast-flux DNS behavior) and explains the mechanism (multiple rounds of A/AAAA queries, IP rotation across rounds). This clearly distinguishes it from siblings like check_ns, check_dnssec, or check_lookalikes, which target entirely different DNS signals.

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 implies its use case (identifying botnet/malicious infrastructure) but never states when to prefer this over alternatives such as check_shadow_domains or check_realtime_threat_feed, nor any prerequisites or exclusions. Usage is only inferable from the threat-detection framing.

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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