---
title: "MCP Gateway"
url: "/docs/mcp-gateway/"
kind: "hub"
summary: "Serve tools to agents over MCP: REST and OpenAPI backends as tools, federated MCP servers, tool search, code mode, authorization and discovery over xDS."
---

> Arion site index: [/llms.txt](/llms.txt)

# MCP Gateway

Serve tools to agents over MCP: REST and OpenAPI backends as tools, federated MCP servers, tool search, code mode, authorization and discovery over xDS.

Arion in front of tools for agents: REST backends, OpenAPI documents and upstream MCP servers exposed as one MCP endpoint, with per-tool authorization, tool search and dynamic discovery. In code mode, agents send one script that composes many tools, and Arion runs it in a sandbox.