Document updated on Sep 17, 2025

MCP Server

The MCP Server feature exposes any of your existing use cases as MCP tools so you can allow to AI MCP Agents to access any of the systems you have already, or create new ones easily, whether it is based on legacy services and data or not.

With the MCP Server of KrakenD, you instantly add MCP to all your stack regardless of their native MCP compatibility or not. This unlocks effortless AI-driven integrations by bridging any service with MCP through declarative configuration.

As KrakenD can expose through MCP any kind of service, you can start offering endless use cases, and is a game changer to start publishing AI services inside enterprise architectures with no effort.

The key concepts of the MCP server are:

• Build on-the-fly MCP servers: Declare and run MCP servers that fetch and send data from and to multiple places.
• Protocol translation: Offer MCP, consume anything. E.g., connect to a SOAP service and offer it to Claude via MCP.
• KrakenD ecosystem compatibility: MCP servers are first-class citizens and enjoy authorization, throttling, data modification, validation, caching, monitoring, workflows and everything else on KrakenD.
• Declarative simplicity: Minimal config additions get powerful AI-optimized APIs in front of any service.
• Multi-tool support: Expose multiple AI tools with individual input/output JSON schemas and workflows per MCP server, including mediatypes like audio and images.
• Stateless or stateful operations: Choose behavior to align with backend semantics, SSE available too.

MCP Server configuration overview

To start serving MCP on KrakenD, two main configuration sections define MCP Servers:

1. MCP server declaration (root extra_config with ai/mcp)
2. MCP entrypoint configuration (endpoint’s extra_config with ai/mcp)

MCP Server configuration

The ai/mcp namespace at the root level contains all the configuration related to MCP. In this section you declare the list of servers available to agents, and plug them to specific services.

Here’s a real world configuration example you can test:

{
  "$schema": "https://krakend.io/schema/v2.12/krakend.json",
  "version": 3,
  "extra_config": {
    "ai/mcp": {
      "servers": [
        {
          "instructions": "Provides the current state of city webcams",
          "name": "webcam-status",
          "title": "Webcam tools",
          "version": "1.0.1",
          "tools": [
            {
              "name": "rovaniemi-webcam",
              "title": "Rovaniemi webcam",
              "description": "Get the latest image from the Rovaniemi webcam",
              "type": "image",
              "workflow": {
                "endpoint": "/__mcp/rovaniemi-webcam",
                "output_encoding": "no-op",
                "backend": [
                  {
                    "url_pattern": "/vi/Cp4RRAEgpeU/0.jpg",
                    "host": [
                      "https://img.youtube.com"
                    ]
                  }
                ]
              }
            }
          ]
        }
      ]
    }
  },
  "endpoints": [
    {
      "endpoint": "/mcp",
      "method": "POST",
      "timeout": "10s",
      "backend": [
        {
          "url_pattern": "/ignore",
          "host": [
            "ignore"
          ]
        }
      ],
      "extra_config": {
        "ai/mcp": {
          "server_name": "webcam-status"
        }
      }
    }
  ]
}

The configuration above will allow you an interaction like this:

The list of available fields is:

MCP Entrypoint configuration

Finally, you need to provide a door to use the MCP servers you have defined. Endpoints serve as entrypoints, and you declare a route (most vendors use /mcp), and then plug it to the server you have defined above. Make sure to reuse the exact name you wrote in the server definition.

For example:

{ "version": 3,
  "endpoints": [
    {
      "endpoint": "/mcp",
      "method": "POST",
      "timeout": "10s",
      "backend": [
        {
          "url_pattern": "/ignore",
          "host": [
            "ignore"
          ]
        }
      ],
      "extra_config": {
        "ai/mcp": {
          "server_name": "webcam-status"
        }
      }
    },
    {
      "endpoint": "/mcp",
      "method": "DELETE",
      "@comment": "Allows the client to mark the session as deleted to free up memory",
      "backend": [
        {
          "url_pattern": "/ignore",
          "host": [
            "ignore"
          ]
        }
      ],
      "extra_config": {
        "ai/mcp": {
          "server_name": "webcam-status"
        }
      }
    }
  ]
}

You can write any value on the host and url_pattern of your backend, as once you add the ai/mcp these become irrelevant (the endpoint connects to the MCP server you just created). On the timeout make sure to use a value that is suitable for the services you are exposing through MCP.