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What is MCPX?​

MCPX is the Control Plane for your agents.

It gives you a single, powerful gateway to manage how AI agents access real-world tools—securely, observably, and at scale. Whether you're prototyping with Claude or deploying to production, MCPX ensures your agents interact with tools the right way, every time.

Why MCPX?​

As agents become more capable, their access to APIs and services must be governed, secured, and monitored just like any other production system. MCPX delivers:

  • Centralized access: Aggregate and expose tool servers through a unified endpoint.
  • Policy enforcement: Control which tools and methods are accessible to which agents.
  • Full observability: Track usage, token cost, latency, and errors across all tool calls.
  • Production readiness: Container-native, CI/CD-friendly, and built for real-world deployment.

With MCPX, you can safely connect your agents to anything, without losing control.

Architecture​

MCPX is designed as a lightweight, powerful middleware layer between your client (or LLM agent) and one or more MCP-compatible tool servers. Instead of wiring agents directly to individual tool servers, MCPX exposes a single entry point that transparently handles spawning, routing, and communication with backend services.

MCPX Architecture

The key characteristics of MCPX are:

Single Entry Point
MCPX provides a unified HTTP interface using Server-Sent Events (SSE), so your LLM or client only needs to connect to one API surface. No need to manage dozens of tool endpoints.

Subprocess Communication via stdio
Backend MCP-compatible tools are launched as subprocesses using the stdio transport defined by the Model Context Protocol (MCP). This ensures lightweight, language-agnostic execution.

Dynamic Routing & Multiplexing
MCPX dispatches tool calls to the appropriate tool based on your configuration—whether you're running one tool or many. This allows teams to scale and swap tools without changing client logic.

Policy & Access Control Ready
Route-level and tool-level access can be enforced via config-defined access policies, ensuring each agent or user only accesses what they’re allowed to.

Zero-Config for Clients
Your agent or client doesn’t need to know what tools exist or where they live—just point it at MCPX and let it handle the orchestration.

Features at a Glance​

FeatureDescription
Access Control ListDefine global, service-level, or tool-level access per consumer group using the x-lunar-consumer-tag header.
API Key AuthenticationOptional API key auth using x-lunar-api-key, configured via the API_KEY environment variable.
Tool GroupingOrganize tools into logical groups using toolGroups for fine-grained access or routing.
Lunar Gateway IntegrationSeamlessly connect with Lunar Gateway by setting LUNAR_PROXY_HOST for downstream proxying.
Built In MetricsExposes Prometheus-compatible metrics (/metrics) including detailed tool_call_duration_ms histograms.

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