MCP Servers — WrongStack

Connect any Model Context Protocol server to WrongStack and use its tools as if they were built-in.

Supported Transports

Quick Start

// ~/.wrongstack/config.json
{
  "mcpServers": {
    "filesystem": {
      "enabled": true
    }
  }
}

Then run wstack — the filesystem server is now active with tools like mcp__filesystem__read_file, mcp__filesystem__write_file, etc.

Built-in Server Presets

WrongStack bundles configs for popular MCP servers. Enable them with:

# Add a server (disabled by default)
wstack mcp add filesystem

# Add and enable immediately
wstack mcp add github --enable
wstack mcp add minimax-vision --enable

# List configured servers
wstack mcp list

Available Presets

Manual Configuration

{
  "mcpServers": {
    "my-server": {
      "name": "my-server",
      "description": "My custom MCP server",
      "transport": "stdio",
      "command": "npx",
      "args": ["-y", "@my-org/mcp-server", "--verbose"],
      "enabled": true,
      "permission": "confirm",
      "allowedTools": ["read", "search"],
      "startupTimeoutMs": 10000,
      "requestTimeoutMs": 60000
    }
  }
}

Configuration Reference

interface MCPServerConfig {
  name: string;
  transport: 'stdio' | 'sse' | 'streamable-http';

  // stdio — local binary
  command?: string;    // e.g. "npx", "/usr/local/bin/my-mcp-server"
  args?: string[];
  env?: Record<string, string>;

  // sse / streamable-http — remote
  url?: string;
  headers?: Record<string, string>;

  // Common options
  enabled?: boolean;          // default: true
  allowedTools?: string[];    // whitelist — undefined = all tools
  permission?: Permission;    // 'auto' | 'confirm' | 'deny'  (default: 'confirm')
  startupTimeoutMs?: number;  // default: 10000
  requestTimeoutMs?: number;  // default: 60000
  description?: string;        // shown in `wstack mcp list`
}

MCP Tool Naming

All MCP tools are prefixed with mcp__<server-name>__ to prevent collision:

mcp__github__list_issues
mcp__github__create_pull_request
mcp__filesystem__read_file
mcp__filesystem__write_file

This means you can have a built-in read_file tool AND mcp__filesystem__read_file without conflict.

Permission Model

All MCP tools default to permission: 'confirm' regardless of whether they look read-only. This means the agent asks before using them. You can:

1. Trust a server — set permission: 'auto' in the server config (all tools run without asking)
2. Trust specific tools — use a trust policy config (see Config type):

   { "mcp__github__*": { "auto": true } }

3. Deny a server — set permission: 'deny' (tools exist but agent must explicitly request confirmation)

Reconnection

• stdio servers: If the child process exits, WrongStack automatically retries up to 3 times with exponential backoff (500ms → 1s → 2s). After 3 failures the server is marked failed and tools are unregistered.
• HTTP servers (SSE / streamable-http): If the SSE read loop errors, the transport transitions to disconnected and the registry schedules a reconnect.

Troubleshooting

Server fails to start

Check that:

• The command is in your PATH (or use an absolute path)
• npx -y @modelcontextprotocol/server-filesystem . works standalone
• The startupTimeoutMs is sufficient for slow-starting servers
• The requestTimeoutMs is sufficient for long-running tool calls

Tools not appearing

wstack mcp list          # shows configured servers + state
wstack diag              # shows MCP health under "MCP Servers:"

Connection drops repeatedly

This usually means the server process crashes on startup. Try running it manually:

node /path/to/server/script.js
# then type: {"jsonrpc":"2.0","id":1,"method":"initialize","params":{...}}

allowedTools not filtering

Restart after changing allowedTools — the tool list is cached after discovery.

Writing Your Own MCP Server

Any server that implements the MCP spec works with WrongStack. Minimal example:

// server.js — stdio MCP server
import { createInterface } from 'readline';

const rl = createInterface({ input: process.stdin, terminal: false });
rl.on('line', async (line) => {
  const req = JSON.parse(line);
  if (req.method === 'initialize') {
    process.stdout.write(JSON.stringify({
      jsonrpc: '2.0', id: req.id,
      result: { protocolVersion: '2024-11-05', capabilities: { tools: {} }, serverInfo: { name: 'my-server', version: '1.0.0' } }
    }) + '\n');
    process.stdout.flush();
  } else if (req.method === 'tools/list') {
    process.stdout.write(JSON.stringify({
      jsonrpc: '2.0', id: req.id,
      result: { tools: [{ name: 'greet', description: 'Say hello', inputSchema: { type: 'object', properties: { name: { type: 'string' } } } }] }
    }) + '\n');
    process.stdout.flush();
  }
});

Then in your config:

{
  "mcpServers": {
    "my-server": {
      "transport": "stdio",
      "command": "node",
      "args": ["/path/to/server.js"]
    }
  }
}