MCPC

Build agentic MCP servers by composing existing MCP tools.

MCPC is the SDK for building agentic MCP (Model Context Protocol) Servers. You
can use it to:

1. Create Powerful Agentic MCP Tools: Simply describe your vision in text
and reference tools from the
expanding MCP community.
As standard MCP tools, your agents work everywhere and collaborate
seamlessly.
2. Fine-Tune Existing Tools: Flexibly modify existing tool descriptions and
parameters, or wrap and filter results to precisely adapt them to your
specific business scenarios.
3. Build Multi-Agent Systems: By defining each agent as a MCP tool, you can
compose and orchestrate them to construct sophisticated, collaborative
multi-agent systems.

Key Features

- Portability and agent interoperability: Build once, run everywhere as MCP
tools - agents work across all MCP clients and can discover and collaborate
with each other through standard MCP interfaces
- Simple composition and fine-tuning: Compose MCP servers as building
blocks, select and customize tools, or modify their descriptions and
parameters
- Logging and tracing: Built-in MCP logging and OpenTelemetry tracing
support
- Skills support: Define domain-specific knowledge following the
Agent Skills specification - deploy to production,
share via MCP, and declare tool dependencies
- Flexible execution modes: Multiple specialized modes to fit different
scenarios - interactive agent (agentic), AI SDK sampling (ai_sampling), AI
ACP mode (ai_acp), secure code execution
(code_execution), and sandbox + sampling
(code_execution_sampling) - each
with dedicated implementations

Quick Start

Three Ways to Get Started

1. Use the Website (Fastest)

Visit mcpc.tech to browse servers from the official MCP
registry, discover tools, and generate ready-to-use agents.

2. Use the Agent (Interactive)

Let AI help you discover servers and build agents:

Add to your MCP client:

{
  "mcpServers": {
    "mcpc-builder-agent": {
      "command": "npx",
      "args": ["-y", "@mcpc-tech/builder", "mcpc-builder-agent"]
    }
  }
}

3. Write Code (Full Control)

Use the SDK directly for complete customization. See examples below.

---

Installation

# npm (from npm registry)
npm install @mcpc-tech/core
npm (from jsr)
npx jsr add @mcpc/core
deno
deno add jsr:@mcpc/core
pnpm (from npm registry)
pnpm add @mcpc-tech/core
pnpm (from jsr)
pnpm add jsr:@mcpc/core

Or run directly with the CLI (no installation required):

# Run with remote configuration
npx -y @mcpc-tech/cli --config-url \
  "https://raw.githubusercontent.com/mcpc-tech/mcpc/main/packages/cli/examples/configs/codex-fork.json"

Examples: Create a Simple Codex/Claude Code Fork

import { mcpc } from "@mcpc/core";
const server = await mcpc(

  [{ name: "coding-agent", version: "0.1.0" }, { capabilities: { tools: {} } }],

  [{

    name: "coding-agent",

    description: 

      You are a coding assistant with advanced capabilities.

Your capabilities include:

      - Reading and writing files

      - Executing terminal commands to build, test, and run projects

      - Interacting with GitHub to create pull requests and manage issues
Available tools:

      <tool name="desktop-commander.execute_command" />

      <tool name="desktop-commander.read_file" />

      <tool name="desktop-commander.write_file" />

      <tool name="github.create_pull_request" />

    ,

    deps: {

      mcpServers: {

        "desktop-commander": {

          command: "npx",

          args: ["-y", "@wonderwhy-er/desktop-commander@latest"],

          transportType: "stdio",

        },

        github: {

          transportType: "streamable-http",

          url: "https://api.githubcopilot.com/mcp/",

        },

      },

    },

  }],

);

> Complete Example: See the full
> Codex fork tutorial.

Install the MCPC Core Skill

Install the mcpc-core skill into your project using
skills.sh:

npx skills add mcpc-tech/mcpc

This installs the skill into .agents/skills/mcpc-core/, giving your agent
on-demand access to the full @mcpc/core API reference, usage patterns, plugin
guide, and gotchas.

---

Examples: Load Agent Skills

For complex agents where inline description becomes unwieldy, use
Agent Skills to organize domain knowledge in separate
files that are loaded on-demand.

import { createBashPlugin, createSkillsPlugin } from "@mcpc/core/plugins";
const server = await mcpc(

  [{ name: "my-agent", version: "1.0.0" }, { capabilities: { tools: {} } }],

  [{

    name: "my-agent",

    description: 'An agent with domain knowledge\n\n<tool name="bash"/>',

    plugins: [

      createSkillsPlugin({ paths: ["./skills"] }),

      createBashPlugin(),

    ],

  }],

);

Skills load domain knowledge on-demand, while bash plugin enables script
execution. For scripts in scripts/ directory, skills returns the path - use
bash tool to execute.

> Complete Examples: See
> 14-skills-plugin.ts and
> 25-skills-with-bash.ts.

Examples: Progressive Manual Disclosure

For agents with detailed instructions, use the manual field to reduce initial
prompt length - the full manual is fetched on-demand via man { manual: true }:

const server = await mcpc(
  [{ name: "code-reviewer", version: "1.0.0" }, {
    capabilities: { tools: {} },
  }],
  [{
    name: "code-reviewer",
    description: "AI code reviewer for quality and security analysis.",
    manual: Detailed review guidelines...
<tool name="desktop-commander.read_file"/>
<tool name="desktop-commander.write_file"/>
Review Categories
1. Code Quality - readability, naming, complexity
2. Security - SQL injection, XSS, credentials
...,
    deps: {
      mcpServers: {
        "desktop-commander": {
          command: "npx",
          args: ["-y", "@wonderwhy-er/desktop-commander@0.1.20"],
          transportType: "stdio",
        },
      },
    },
  }],
);

> Complete Example: See
> 21-progressive-manual.ts.

How It Works

Three simple steps:

1. Define dependencies - List the MCP servers you want to use
2. Write agent description - Describe what your agent does and reference
tools
3. Create server - Use mcpc() to build and connect your server

Execution Modes

MCPC provides multiple flexible execution modes to fit different scenarios:

| Mode | Description | Use Case | Requires Plugin |
| ------------------------- | --------------------------------------------- | ---------------------------------------------------- | --------------- |
| agentic | Interactive step-by-step execution | Standard agent interactions | Built-in |
| ai_sampling | AI SDK sampling mode | Autonomous AI SDK execution | Built-in |
| ai_acp | AI SDK ACP mode | Coding agents (Claude Code, etc.) | Built-in |
| code_execution | Secure JavaScript sandbox with tool access | Code generation and execution | External |
| code_execution_sampling | Secure sandbox plus MCP sampling-backed calls | Sandbox execution that can also ask the client model | External |

> Note: agentic, ai_sampling, and ai_acp are built-in modes — just set
> options.mode and they work. code_execution and code_execution_sampling
> require installing and loading their respective plugin packages.

Quick Example

// Interactive agent (default)
{ options: { mode: "agentic" } }
// Autonomous agent

{ options: { mode: "ai_sampling", samplingConfig: { maxIterations: 10 } } }
// Code execution with sandbox

import { createCodeExecutionPlugin } from "@mcpc/plugin-code-execution/plugin";

{

  plugins: [createCodeExecutionPlugin()],

  options: { mode: "code_execution" }

}

> Detailed Documentation: See
> Execution Modes Guide for comprehensive information
> on each mode, configuration options, and best practices.

Documentation

- Getting Started - Installation and
first steps
- Creating Your First Agent -
Complete tutorial
- Execution Modes - Comprehensive guide to all
execution modes
- CLI Usage Guide - Using the MCPC CLI
- Logging and Tracing - MCP logging and
OpenTelemetry tracing
- Examples - Real-world use cases
- FAQ - Common questions and answer

Examples

See working examples in the examples directory or
check out the Codex fork tutorial.

Contributing

We welcome contributions! See CONTRIBUTING.md for details.

License

MIT License - see LICENSE for details.