MCP Aggregation Protocol (MCP-AX): Hierarchical Tool Namespace Delegation for Model Context Protocol Servers

This document specifies MCP-AX, an aggregation protocol for Model Context Protocol (MCP) servers. MCP-AX enables hierarchical composition of tool namespaces across heterogeneous networks of MCP servers, from cloud services to resource-constrained embedded devices. The protocol defines a master-subagent architecture directly inspired by the AgentX protocol (RFC 2741), adapted for the tool/resource model of MCP rather than the OID/MIB model of SNMP. MCP-AX introduces recursive namespace delegation, capability-aware routing, transport bridging for constrained nodes, and irreversibility-gated tool dispatch suitable for autonomous and semi- autonomous AI agent systems.