Uptimeify

dmarc_check

Read-only

Fetch a domain's DMARC record from _dmarc. and evaluate it: the raw record, every parsed tag, the policy and subdomain policy, the percentage the policy applies to, and warnings for records that parse but do not protect (p=none, missing rua, syntax receivers ignore). Reports the published policy, not whether real mail passes it. Pair it with spf_check and dkim_check, the mechanisms DMARC aligns against. Anonymous and rate-limited per IP.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`domain`	Yes	Domain name, e.g. deinkunde.com

Output Schema

TableJSON Schema

Name	Required	Description	Default
`ok`	No
`pct`	No
`tags`	No
`error`	No
`found`	No
`domain`	No
`policy`	No
`record`	No
`warnings`	No
`subPolicy`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed17 schema fields changedSep 11, 2026

removedOutput schema / properties / domain / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / domain / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / error / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / error / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / found / anyOf

Removed value: -[
-  {
-    "type": "boolean"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / found / type
```
Added value: +[
+  "boolean",
+  "null"
+]
```

removedOutput schema / properties / ok / anyOf

Removed value: -[
-  {
-    "type": "boolean"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / ok / type

Added value: +[
+  "boolean",
+  "null"
+]

removedOutput schema / properties / pct / anyOf

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / pct / type

Added value: +[
+  "number",
+  "null"
+]

removedOutput schema / properties / policy / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / policy / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / record / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / record / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / subPolicy / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / subPolicy / type
```
Added value: +[
+  "string",
+  "null"
+]
```

changedOutput schema / properties / tags / anyOf

Previous value: -[
-  {
-    "items": {
-      "additionalProperties": {},
-      "properties": {
-        "tag": {
-          "anyOf": [
-            {
-              "type": "string"
-            },
-            {
-              "type": "null"
-            }
-          ]
-        },
-        "value": {
-          "anyOf": [
-            {
-              "type": "string"
-            },
-            {
-              "type": "null"
-            }
-          ]
-        }
-      },
-      "type": "object"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": {},
+      "properties": {
+        "tag": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "value": {
+          "type": [
+            "string",
+            "null"
+          ]
+        }
+      },
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

Changed1 schema field changedAug 4, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "properties": {
+    "domain": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "error": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "found": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "ok": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "pct": {
+      "anyOf": [
+        {
+          "type": "number"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "policy": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "record": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "subPolicy": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "tags": {
+      "anyOf": [
+        {
+          "items": {
+            "additionalProperties": {},
+            "properties": {
+              "tag": {
+                "anyOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              },
+              "value": {
+                "anyOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              }
+            },
+            "type": "object"
+          },
+          "type": "array"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "warnings": {
+      "anyOf": [
+        {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    }
+  },
+  "type": "object"
+}

First observedAug 4, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations only declare readOnlyHint=true, so the description carries most of the load. It adds genuinely useful behavioral context: anonymous access, per-IP rate limiting, the resolution path (_dmarc.<domain>), and that warnings are emitted for records that parse but do not protect. It stops short of describing failure modes such as what happens when no record exists or how rate limiting manifests.

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 dense sentences with the core action front-loaded and no filler; the enumeration of returned fields is the most valuable content and arrives early. It is slightly run-on, packing the lookup, the return shape, the caveat, and the rate-limit note into one long sentence, which costs a little readability.

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?

For a single-param read tool with an output schema, the description supplies everything an agent needs: the lookup mechanism, what is returned, the p=none/missing-rua warning behavior, the alignment caveat, related tools, and the anonymous/rate-limited access model. Nothing material is left for the agent to infer before calling it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 100% schema description coverage the baseline is 3, but the description goes slightly beyond the schema by explaining that the domain feeds a DNS lookup against the reserved _dmarc.<domain> name, which clarifies what the parameter is actually resolved against. That is meaningful added context, though format rules (IDN, trailing dot, subdomain handling) are not addressed.

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 (fetch) and resource (a domain's DMARC record from _dmarc.<domain>) plus what is done with it (evaluate tags, policy, subdomain policy, percentage, warnings). It also names the sibling tools it complements, spf_check and dkim_check, so an agent can place it among the 19 siblings without opening a 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?

Gives clear context for use, including the boundary 'Reports the published policy, not whether real mail passes it', which tells the agent when this tool is the wrong choice for a deliverability question. It also recommends pairing with spf_check and dkim_check. It does not name an explicit alternative tool to use instead for the excluded case, so it falls short of a 5.

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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