MCP Server Management

This guide covers managing MCP servers in Cosine CLI, troubleshooting common issues, and building custom servers.

Using MCP Tools

Once configured, MCP tools appear as available tools in Cosine. The AI will:

1. Discover tools automatically when starting a session
2. Suggest relevant tools based on your requests
3. Request approval before executing tools (unless auto-accept is enabled)

Example Interactions

File System Operations:

You: Read the README.md file in my documents folder
Cosine: I'll read that file for you. [Uses mcp_filesystem tool]

Database Queries:

You: What tables are in my postgres database?
Cosine: Let me check the database schema. [Uses mcp_postgres tool]

GitHub Operations:

You: Create an issue titled "Bug in login flow" in my repo
Cosine: I'll create that issue. [Uses mcp_github tool]

Security Considerations

Tool Approval

By default, Cosine asks for your approval before executing any MCP tool. You can see:

• Which tool is being called
• What arguments are being passed
• The expected outcome

To auto-accept all tool executions (use with caution):

cos start --auto-accept

Environment Variables

For sensitive data like API keys:

• Store them in the env field of your MCP config
• Consider using environment variable references
• Never commit mcp.json with secrets to version control

{
  "mcpServers": {
    "api": {
      "transport": "stdio",
      "command": "node",
      "args": ["/path/to/server.js"],
      "env": {
        "API_KEY": "${MY_API_KEY}"
      }
    }
  }
}

Scope of Access

Each MCP server only has access to what you configure:

• File system servers: Only see directories you specify
• API servers: Only have permissions of the tokens you provide
• Database servers: Only access to the connection string you configure

Popular MCP Servers

Here’s a list of official and community MCP servers you can use:

Official Anthropic Servers

Server	Install Command	Description
Filesystem	npx -y @modelcontextprotocol/server-filesystem /path	Read/write files in allowed directories
GitHub	npx -y @modelcontextprotocol/server-github	Repository operations, issues, PRs
Git	npx -y @modelcontextprotocol/server-git	Git operations on local repos
PostgreSQL	npx -y @modelcontextprotocol/server-postgres <connection>	Database queries
SQLite	npx -y @modelcontextprotocol/server-sqlite <db>	SQLite database access
Slack	npx -y @modelcontextprotocol/server-slack	Send messages, channel operations
Brave Search	npx -y @modelcontextprotocol/server-brave-search	Web search via Brave API
Fetch	npx -y @modelcontextprotocol/server-fetch	HTTP requests to any URL
Puppeteer	npx -y @modelcontextprotocol/server-puppeteer	Browser automation

Community Servers

For more MCP servers from the community, visit the MCP Servers Repository.

Troubleshooting

Server Not Appearing

If an MCP server doesn’t appear in the tool list:

1. Check the server is properly configured in ~/.cosine/mcp.json
2. Verify the command is installed and available in your PATH
3. Check for JSON syntax errors in the config file
4. Try restarting Cosine

Connection Errors

If you see connection errors:

1. Verify the server URL (for HTTP transport) is correct and accessible
2. Check that required environment variables are set
3. For stdio servers, test the command manually in your terminal

Tool Execution Failures

If tools fail to execute:

1. Check the Cosine output for error messages
2. Verify the MCP server has the necessary permissions
3. Review the server’s documentation for configuration requirements

Building Custom MCP Servers

You can build your own MCP servers to integrate proprietary tools or custom APIs. MCP servers can be built in any language and communicate via the standard MCP protocol.

Resources for Building Servers

• MCP Protocol Documentation
• Python SDK
• TypeScript SDK

Quick Example (Python)

from mcp.server import Server
from mcp.types import TextContent

app = Server("my-server")

@app.tool()
def search_docs(query: str) -> str:
    """Search documentation for a query."""
    # Your implementation here
    return f"Results for: {query}"

if __name__ == "__main__":
    app.run()

Quick Example (TypeScript)

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

const server = new Server({
  name: 'my-server',
  version: '1.0.0',
}, {
  capabilities: {
    tools: {},
  },
});

server.setRequestHandler(CallToolRequestSchema, async (request) => {
  if (request.params.name === 'search_docs') {
    const { query } = request.params.arguments;
    return {
      content: [{ type: 'text', text: `Results for: ${query}` }],
    };
  }
  throw new Error('Tool not found');
});

const transport = new StdioServerTransport();
await server.connect(transport);

Next Steps

• MCP Configuration - Learn about MCP configuration basics
• MCP Examples - See example configurations for popular MCP servers
• Configuration - Learn about general CLI configuration