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http_headers

Read-only

Fetch a URL and return its HTTP response headers verbatim as a name/value map, with the status line and every redirect hop taken to get there. Use it to inspect caching, security and server headers as they are actually sent; the response body is never returned, so this says nothing about page content. For a plain up/down verdict use website_status, for the redirect chain alone redirect_check. Anonymous and rate-limited per IP; hosts resolving to private or reserved address space are refused.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
urlYesFull URL, e.g. https://deinkunde.com

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
okNo
urlNo
statusNo
headersNo
redirectsNo
statusTextNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed9 schema fields changed
    • 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"
      +]
  2. Changed1 schema field changed
    • 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"
      +}
  3. First observed

TDQS

A4.7/5.0
Behavior5/5

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

Beyond the readOnlyHint annotation, it discloses that access is anonymous and rate-limited per IP, that private/reserved address ranges are refused, and that the body is never returned. These are non-obvious operational constraints an agent needs before calling.

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?

Front-loads the core behavior, then exclusions, then routing to alternatives, then operational caveats, in three tight sentences with no filler.

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?

The return shape is described (name/value map plus status line and redirect hops) and an output schema exists, so nothing further about returns is needed. Safety, routing, and access constraints are all covered for a simple one-parameter read tool.

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 coverage is 100% and the single url parameter already has a format example, so the description adds no parameter-level syntax or constraints. Baseline 3 applies when the schema carries the parameter burden.

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 (fetch a URL, return its HTTP response headers) plus exact scope: status line and every redirect hop, body never returned. It explicitly distinguishes itself from siblings website_status and redirect_check, so an agent can route 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 Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit use case ('inspect caching, security and server headers as they are actually sent') and names the two alternatives with their selecting conditions: website_status for a plain up/down verdict, redirect_check for the redirect chain alone.

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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