Uptimeify

HTTP headers

http_headers

Read-only

Fetches a URL and returns its HTTP response headers verbatim as a name/value map, with the status line and every redirect hop. The response body is never returned. website_status gives a plain up/down verdict and redirect_check the redirect chain alone. Anonymous, rate-limited per IP; private and reserved addresses are refused.

Input Schema

Name	Required	Description	Default
`url`	Yes	Full URL, e.g. https://deinkunde.com

Output Schema

Name	Required	Description	Default
`ok`	No
`url`	No
`status`	No
`headers`	No
`redirects`	No
`statusText`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed9 schema fields changedSep 11, 2026

removedOutput schema / properties / ok / anyOf

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

addedOutput schema / properties / ok / type

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

changedOutput schema / properties / redirects / anyOf

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

removedOutput schema / properties / status / anyOf

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

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

removedOutput schema / properties / statusText / anyOf

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

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

removedOutput schema / properties / url / anyOf

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

addedOutput schema / properties / url / type

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

Changed1 schema field changedAug 4, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "properties": {
+    "headers": {
+      "anyOf": [
+        {
+          "additionalProperties": {
+            "type": "string"
+          },
+          "propertyNames": {
+            "type": "string"
+          },
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "ok": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "redirects": {
+      "anyOf": [
+        {
+          "items": {
+            "additionalProperties": {},
+            "properties": {
+              "from": {
+                "anyOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              },
+              "status": {
+                "anyOf": [
+                  {
+                    "type": "number"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              },
+              "to": {
+                "anyOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              }
+            },
+            "type": "object"
+          },
+          "type": "array"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "status": {
+      "anyOf": [
+        {
+          "type": "number"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "statusText": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "url": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    }
+  },
+  "type": "object"
+}

First observedAug 4, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already flag readOnlyHint and openWorldHint, but the description goes well beyond them: the response body is never returned, redirect hops are included, the call is anonymous and rate-limited per IP, and private/reserved addresses are refused. These are concrete behavioral details an agent needs before invoking.

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?

Every sentence earns its place: the core behavior is front-loaded, then the body omission, then the sibling routing, then the auth/access constraints. No redundant restatement of the name or annotations.

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?

The tool has an output schema, so return-value documentation is unnecessary. The description covers alternatives, safety, privacy constraints, and rate limiting. It is fully complete for invocation; only a minor note about pagination or timeouts could be added, but nothing essential 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?

With a single parameter and 100% schema description coverage, the schema already carries the parameter semantics. The description adds no format, encoding, or example beyond what the schema provides, so the baseline of 3 is appropriate.

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?

The description states a precise verb (fetches) and resource (URL returns HTTP response headers verbatim as a name/value map), and clarifies the exact scope: status line plus every redirect hop, never the body. It explicitly distinguishes itself from the sibling tools website_status and redirect_check.

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?

It names both alternatives and the condition that selects them: website_status for a plain up/down verdict, redirect_check for the redirect chain alone. It also states operational constraints (anonymous, rate-limited per IP, private/reserved addresses refused), so an agent knows when the call is appropriate and when it will be rejected.

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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