@xplainer/mcp-server

Backend-agnostic MCP tool registration for the eight explainer tools. createMcpServer(backend, options?) builds an McpServer, walks TOOL_NAMES from @xplainer/protocol, and registers every tool with the title, description and schemas the generated manifest carries. Every surface that serves the contract mounts this same registration, so there is exactly one implementation of what the tools are.

npm i @xplainer/mcp-server

import { createMcpServer, type RenderBackend } from "@xplainer/mcp-server";

const backend: RenderBackend = {
  /* one method per tool: explainer_create, explainer_put_source, … */
};

const server = createMcpServer(backend);

RenderBackend is the seam. This package knows the shape of a call and nothing about how it is answered — @xplainer/cli answers it from the local disk, and a hosted service answers the same interface over its own storage.

It also ships the explainer_put_source guard: assertAgentOwnedPaths() refuses a write to any of the five engine-owned files and throws an EngineOwnedPathError, so a backend cannot forget the rule that keeps the composition shell intact.

The exported surface is recorded in api/mcp-server.api.md in the repository.

Docs

• Architecture — the members and the dependency direction
• Decision records — the tool contract is ADR 0007, file ownership is ADR 0018
• Roadmap — what is built and what is not

Licence

Apache-2.0. See LICENSE and NOTICE, both shipped inside this package.