Relationship to MCP

ECP (Execution Control Protocol) is designed to embrace and extend MCP (Model Context Protocol) — not replace it.

Split of concerns

Protocol	Focus
MCP	Tool discovery, tool invocation, structured tool I/O
ECP	Workflows, environments, policies, packaging, run lifecycle

MCP answers: what tools can this model call, and how?
ECP answers: how does this agentic system execute end-to-end under control? Put another way: MCP defines what a model can reach; ECP defines what it should do with that reach — which steps run, in what order, under what control.

How they layer

Models / agents
    → MCP tools (and other capabilities)
        → ECP workflow steps + environment policies
            → Host runtime (Node, browser, …)

An ECP environment can expose MCP-backed capabilities and still apply budgets, approvals, registry freezes, and portable workflow manifests.

MCP adapter

The @executioncontrolprotocol/mcp package can wrap an initialized Ecp and expose tools such as describe, search, validate, run, encode, and decode to MCP clients. That lets agents drive ECP operations without inventing a parallel control plane.

What ECP does not do

Redefine MCP tool calling semantics
Replace agent frameworks or chat UIs
Require YAML Context manifests (Fluent/JSON workflows are the current surface)

Next steps