Uptimeify

dkim_check

Read-only

Fetch and validate the DKIM public key published at a given selector (._domainkey.) and report the parsed tags, key type, key size in bits, and warnings such as a revoked or malformed key. The selector is required and cannot be derived from the domain: read it from a message's DKIM-Signature header, or try the provider's usual value (google, selector1, default, k1). An unused selector returns found=false rather than an error. Anonymous and rate-limited per IP.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`domain`	Yes	Domain name, e.g. deinkunde.com
`selector`	Yes	DKIM selector, e.g. google or default

Output Schema

TableJSON Schema

Name	Required	Description	Default
`ok`	No
`bits`	No
`tags`	No
`error`	No
`found`	No
`domain`	No
`hasKey`	No
`record`	No
`keyType`	No
`selector`	No
`warnings`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed19 schema fields changedSep 11, 2026

removedOutput schema / properties / bits / anyOf

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

addedOutput schema / properties / bits / type
```
Added value: +[
+  "number",
+  "null"
+]
```

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 / hasKey / anyOf

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

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

removedOutput schema / properties / keyType / anyOf

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

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

removedOutput schema / properties / ok / anyOf

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

addedOutput schema / properties / ok / type

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

removedOutput schema / properties / record / anyOf

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

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

removedOutput schema / properties / selector / anyOf

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

addedOutput schema / properties / selector / 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": {
+    "bits": {
+      "anyOf": [
+        {
+          "type": "number"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "domain": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "error": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "found": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "hasKey": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "keyType": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "ok": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "record": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "selector": {
+      "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

A4.7/5.0

Behavior5/5

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

Goes well beyond readOnlyHint=true by disclosing anonymous, per-IP rate-limited access, the non-error found=false outcome for unused selectors, and the warning behaviours (revoked or malformed key). These are operational traits an agent cannot infer from annotations or schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three dense sentences: what it does first, then the non-obvious selector requirement with fallbacks, then the error/rate-limit semantics. No filler and the critical selector guidance is front-loaded where it matters.

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, yet the description still sketches the returned fields and the found=false case; combined with the selector acquisition guidance and rate-limit disclosure, an agent has everything needed to invoke and interpret the call.

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?

Schema coverage is already 100%, so baseline is 3, but the description adds real meaning: that selector cannot be derived from domain, where to find it, and representative values to try. Domain semantics (e.g. deinkunde.com) are left to the schema.

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 pair (fetch and validate) plus the exact resource (the DKIM public key at <selector>._domainkey.<domain>) and enumerates what is reported: parsed tags, key type, key size, and warnings. This clearly separates it from sibling email-auth checks like spf_check and dmarc_check without needing the schemas.

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?

Explains how to obtain the required selector — read it from a DKIM-Signature header or try common provider values (google, selector1, default, k1) — and clarifies that an unused selector yields found=false rather than an error. It stops short of explicitly routing to sibling tools (spf_check/dmarc_check) or stating when this check is unnecessary.

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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