mcpc-core

@mcpc/core — Build Agentic MCP Servers

@mcpc/core lets you compose existing MCP tools into agentic MCP tools. You write a description that references tools via <tool> XML tags, and MCPC wires everything up into a working MCP server.

Installation

# Deno (preferred in this repo)
deno add jsr:@mcpc/core

# npm
npm install @mcpc-tech/core

# pnpm (from JSR)
pnpm add jsr:@mcpc/core

Minimal Example

import { mcpc } from "@mcpc/core";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

const server = await mcpc(
  [{ name: "my-agent", version: "1.0.0" }, { capabilities: { tools: {} } }],
  [{
    name: "file-agent",
    description: `I help manage files.
Available tools:
<tool name="@wonderwhy-er/desktop-commander.read_file"/>
<tool name="@wonderwhy-er/desktop-commander.write_file"/>`,
    deps: {
      mcpServers: {
        "@wonderwhy-er/desktop-commander": {
          command: "npx",
          args: ["-y", "@wonderwhy-er/desktop-commander@latest"],
          transportType: "stdio",
        },
      },
    },
  }],
);

await server.connect(new StdioServerTransport());

Core API

mcpc(serverConf, composeConf?, options?)

Param	Type	Description
serverConf	[ServerMeta, ServerCapabilities]	Name/version + capabilities tuple
composeConf	ComposeInput[]	Array of ComposeDefinition objects or .md file paths
options	McpcOptions	Loader plugins + setup callback

Returns Promise<ComposableMCPServer>.

ComposeDefinition

{
  name: string | null,          // null = composition-only (no tool exposed)
  description?: string,         // Natural language + <tool> XML refs
  manual?: string,              // Progressive disclosure: long docs hidden behind man tool
  deps?: MCPSetting,            // Dependent MCP servers to connect
  plugins?: (ToolPlugin | string)[],  // Runtime plugins
  options?: {
    mode?: "agentic" | "ai_sampling" | "ai_acp",  // default: "agentic"
    maxSteps?: number,          // default: 50
    maxTokens?: number,         // default: 128_000 (ai_sampling only)
    samplingConfig?: SamplingConfig,
    providerOptions?: { modelPreferences?: {...} },  // ai_sampling only
    acpSettings?: { command, args, env, session, persistSession },  // ai_acp only
    tracingEnabled?: boolean,   // OpenTelemetry
    refs?: ToolRefXml[],
  }
}