MCPHub.nvim

A powerful Neovim plugin that integrates MCP (Model Context Protocol) servers into your workflow. Configure and manage MCP servers through a centralized config file while providing an intuitive UI for testing tools and resources. Perfect for LLM integration, offering both programmatic API access and interactive testing capabilities through the :MCPHub command.

MCP Hub Interface

Using Codecompanion Chat plugin

✨ Features

Simple single-command interface (:MCPHub)
Integrated Hub view for managing servers and tools
- Dynamically enable/disable servers and tools to optimize token usage
- Start/stop servers with persistent state
- Enable/disable specific tools per server
- State persists across restarts
Parallel startup for improved performance
Interactive UI for testing tools and resources
Automatic server lifecycle management across multiple Neovim instances
Smart shutdown handling with configurable delay
Both sync and async operations supported
Clean client registration/cleanup
Comprehensive API for tool and resource access

📦 Installation

Using lazy.nvim:

            ```lua

{ "ravitemer/mcphub.nvim", dependencies = { "nvim-lua/plenary.nvim", -- Required for Job and HTTP requests }, build = "npm install -g mcp-hub@latest", -- Installs required mcp-hub npm module config = function() require("mcphub").setup({ -- Required options port = 3000, -- Port for MCP Hub server config = vim.fn.expand("~/mcpservers.json"), -- Absolute path to config file

        -- Optional options
        on_ready = function(hub)
            -- Called when hub is ready
        end,
        on_error = function(err)
            -- Called on errors
        end,
        shutdown_delay = 0, -- Wait 0ms before shutting down server after last client exits
        log = {
            level = vim.log.levels.WARN,
            to_file = false,
            file_path = nil,
            prefix = "MCPHub"
        },
    })
end

}


Example configuration file:

```json
{
  "mcpServers": {
    "fetch": {
      "command": "uvx",
      "args": ["mcp-server-fetch"]
    },
    "todoist": {
      "command": "npx",
      "args": ["-y", "@abhiz123/todoist-mcp-server"],
      "disabled": true,
      "env": {
        "TODOIST_API_TOKEN": "your-api-token-here"
      }
    }
  }
}

Requirements

Neovim >= 0.8.0
Node.js >= 18.0.0
plenary.nvim
mcp-hub (automatically installed via build command)

🚀 Usage

Open the MCPHub UI to manage servers, test tools and monitor status:

:MCPHub

You can:

Start/stop servers directly from the Hub view
Enable/disable specific tools for each server
Test tools and resources interactively
Monitor server status and logs

Use the hub instance in your code:

-- Get hub instance after setup
local mcphub = require("mcphub")

-- Option 1: Use on_ready callback
mcphub.setup({

            
        
            
                    port = 3000,
    config = vim.fn.expand("~/mcpservers.json"),
    on_ready = function(hub)
        -- Hub is ready to use here
    end
})

-- Option 2: Get hub instance directly (might be nil if setup in progress)
local hub = mcphub.get_hub_instance()

-- Call a tool (sync)
local response, err = hub:call_tool("server-name", "tool-name", {
    param1 = "value1"
}, {
    return_text = true -- Parse response to LLM-suitable text
})

-- Call a tool (async)
hub:call_tool("server-name", "tool-name", {
    param1 = "value1"
}, {
    return_text = true,
    callback = function(response, err)
        -- Use response
    end
})

-- Access resource (sync)
local response, err = hub:access_resource("server-name", "resource://uri", {
    return_text = true
})

-- Get prompt helpers for system prompts
local prompts = hub:get_prompts({
    use_mcp_tool_example = [[
weather-server
get_forecast

{
  "city": "San Francisco",
  "days": 5
}

]],
    access_mcp_resource_example = [[
weather-server
weather://san-francisco/current
]]
})
-- prompts.active_servers: Lists currently active servers
-- prompts.use_mcp_tool: Instructions for tool usage with example
-- prompts.access_mcp_resource: Instructions for resource access with example

🔌 Extensions

MCPHub.nvim provides extensions that integrate with popular Neovim chat plugins. These extensions allow you to use MCP tools and resources directly within your chat interfaces.

Available Extensions

CodeCompanion Integration

Add MCP capabilities to CodeCompanion.

Add it as a dependency to load the plugin before codecompanion:

{
  "olimorris/codecompanion.nvim",
  dependencies = {
    "nvim-lua/plenary.nvim",
    "nvim-treesitter/nvim-treesitter",
    "ravitemer/mcphub.nvim"
  },
},

            - Please note there are some breaking changes with codecompanion v13 in the way we configure tools.

  require("codecompanion").setup({
    strategies = {
        chat = {
            tools = {
                ["mcp"] = {
                    callback = require("mcphub.extensions.codecompanion"),
                    description = "Call tools and resources from the MCP Servers",
                    opts = {
                      -- user_approval = true,
                      requires_approval = true,
                    }
                }
            }
        }
    }
  })

See the extensions/ folder for more examples and implementation details.

Avante Integration

The Avante extension automatically updates your [mode].avanterules file (e.g. planning.avanterules) whenever MCP servers or their tools are updated. This ensures Avante always has up-to-date information about available MCP capabilities in its system prompt.

⚠️ Important Loading Behavior: Avante loads rules files only once when first opened after Neovim starts. Changes to enabled/disabled MCP servers will update the rules file, but Avante won't see these changes until you:

Exit Neovim completely
Start Neovim again
Open Avante fresh

Commands like /reset, /new, or /clear do not cause Avante to reload the rules file.

⚠️ Tool Conflicts: Disable any built-in Avante tools that might conflict with enabled MCP servers to prevent duplicate functionality or unexpected behavior.

Setup

Add MCP capabilities to Avante by including the MCP tool in your setup:

require("avante").setup({
    -- other config
    custom_tools = {
        -- optional: mode is "planning" that is when you open the chat using toggle or aa
        --optional: cwd can be a string or a function that should returns path
        require("mcphub.extensions.avante").mcp_tool("planning",function()
          return require("avante.utils").get_project_root()

            
        
            
                        end)
    }
})

⚠️ Warning: File Override Behavior

This extension modifies your [mode].avanterules file. When creating a new file or replacing content, it uses this template:

{% block mcp_servers %}
# Active MCP Servers:
- server1: tool1, tool2
- server2: tool3, tool4

# Available Tools and Resources:
[Detailed list of capabilities...]
{% endblock %}

File handling works as follows:

If file has the MCP servers block:
- Only content within the block is modified
- Content outside the block remains untouched
If no block present:
- ENTIRE FILE CONTENT WILL BE REPLACED
- A new file with proper block structure will be created
- All custom instructions will be lost

To safely use custom instructions:

Add the MCP servers block at the END of your [mode].avanterules file
Put your custom instructions BEFORE the block
Keep the block at the END to prevent MCP content from being overwritten

Example .avanterules file with custom instructions:

# Your Custom Instructions
You should always write tests for your code.
Handle edge cases carefully.

# IMPORTANT: Keep this block at the end of file
{% block mcp_servers %}
[MCP server capabilities will be automatically updated here]
{% endblock %}

Note: You can also access the Express server directly at http://localhost:[port]/api

🔧 Troubleshooting

Environment Requirements
- Ensure these are installed as they're required by most MCP servers:
```
node --version    # Should be >= 18.0.0
python --version  # Should be installed
uvx --version    # Should be installed
```
- Most server commands use npx or uvx - verify these work in your terminal

Port Issues

If you get EADDRINUSE error, kill the existing process:

lsof -i :[port]  # Find process ID
kill [pid]       # Kill the process

Configuration File
- Ensure config path is absolute
```
          - Verify file contains valid JSON with `mcpServers` key
```
- Check server-specific configuration requirements
- Validate server command and args are correct for your system
MCP Server Issues
- Validate server configurations using either:
  - MCP Inspector: GUI tool for verifying server operation
  - mcp-cli: Command-line tool for testing servers with config files
- Check server logs in MCPHub UI (Logs view)
- Test tools and resources individually to isolate issues
Need Help?
- Create a Discussion for questions
- Open an Issue for bugs

🔄 How It Works

MCPHub.nvim uses an Express server to manage MCP servers and handle client requests:

When setup() is called:
- Checks for mcp-hub command installation
- Verifies version compatibility
- Starts mcp-hub with provided port and config file
- Creates Express server at localhost:[port]
After successful setup:
- Calls on_ready callback with hub instance
- Hub instance provides REST API interface
- UI updates in real-time via :MCPHub command
Express Server Features:
- Manages MCP server configurations
- Handles tool execution requests
- Provides resource access
- Multi-client support
- Automatic cleanup
When Neovim instances close:
- Unregister as clients
- Last client triggers shutdown timer
- Server waits shutdown_delay seconds before stopping
- Timer cancels if new client connects

This architecture ensures:

Consistent server management
Real-time status monitoring
Efficient resource usage
Clean process handling
Multiple client support

Architecture Flows

Server Lifecycle

sequenceDiagram
    participant N1 as First Neovim
    participant N2 as Other Neovims

            
        
            
                    participant S as MCP Hub Server

    Note over N1,S: First Client Connection
    N1->>S: Check if Running
    activate S
    S-->>N1: Not Running
    N1->>S: start_hub()
    Note over S: Server Start
    S-->>N1: Ready Signal
    N1->>S: Register Client
    S-->>N1: Registration OK

    Note over N2,S: Other Clients
    N2->>S: Check if Running
    S-->>N2: Running
    N2->>S: Register Client
    S-->>N2: Registration OK

    Note over N1,S: Server stays active

    Note over N2,S: Client Disconnection
    N2->>S: Unregister Client
    S-->>N2: OK
    Note over S: Keep Running

    Note over N1,S: Last Client Exit
    N1->>S: Unregister Client
    S-->>N1: OK
    Note over S: Grace Period
    Note over S: Auto Shutdown
    deactivate S

Request flow

sequenceDiagram
    participant N as Neovim
    participant P as Plugin
    participant S as MCP Hub Server
    N->>P: start_hub()
    P->>S: Health Check
    alt Server Not Running
        P->>S: Start Server
        S-->>P: Ready Signal
    end
    P->>S: Register Client
    S-->>P: Registration OK
    N->>P: :MCPHub
    P->>S: Get Status
    S-->>P: Server Status
    P->>N: Display UI

Cleanup flow

flowchart LR
    A[VimLeavePre] -->|Trigger| B[Stop Hub]
    B -->|If Ready| C[Unregister Client]
    C -->|Last Client| D[Server Auto-shutdown]
    C -->|Other Clients| E[Server Continues]
    B --> F[Clear State]
    F --> G[Ready = false]
    F --> H[Owner = false]

API Flow

sequenceDiagram
    participant C as Chat Plugin
    participant H as Hub Instance
    participant S as MCP Server
    C->>H: call_tool()
    H->>H: Check Ready
    alt Not Ready
        H-->>C: Error: Not Ready
    end
    H->>S: POST /tools
    S-->>H: Tool Result
    H-->>C: Return Result
    Note over C,S: Similar flow for resources

    C->>H: access_resource()
    H->>H: Check Ready
    H->>S: POST /resources
    S-->>H: Resource Data
    H-->>C: Return Data

            ## 🚧 Future Enhancements

Currently planning these features:

Workflow integration with CodeCompanion for enhanced code assistance
Enhanced help view with comprehensive documentation
Community marketplace for sharing and discovering MCP servers
Add custom descriptions for each MCP server through the UI
Support server-specific configuration through the interface

👏 Acknowledgements

Thanks to:

nui.nvim for inspiring our text highlighting utilities

mcphub.nvim

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