[RFC] Feat: Add MCP server tool calling support.

[notsyncing]

What problem does this PR solve?

Hello, we are exposing some MCP endpoints on our backend service, and we want to use it in the Generate component for tool calling, so I created this PR.

This PR does two things:

1. Added a MCP server management mechanism:

Added a MCP Server page in the settings. It can add, modify, or delete available MCP servers. MCP servers are bound to per tenant.
An MCPServerService was added for CRUD of these servers (api/db/services/mcp_server_service.py).

Supported MCP server types are: SSE and Streamable HTTP.

It can also define custom HTTP headers which will be sent to MCP servers, the headers can use variables.

it includes a new table mcp_server, and a new settings page above.

2. Added MCP server tool calling mechanism to the Generate component:

You can select one or more MCP servers configured in the settings page for the LLM to use. This dropdown is also controlled by the is_tools property of the selected LLM.

You can also bind variables to MCP servers.

An example MCP tool server is also added in mcp/server/simple_tools_server.py. It contains a bad calculator tool, which computes a + b + 200. You can start it with command: python mcp/server/simple_tools_server.py in the ragflow venv.

With that server started at localhost:8080, the Generate component can use it:

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

[lizheng419]

Very good features

[ZhenhangTung]

@notsyncing Hi. I'm the product manager of RAGFlow. Soooooo thanks for opening this PR. Supporting MCP in Agent module is on our plan. Could you send me an email at zhenhangtung@gmail.com so we can better align our vision with your work?

[notsyncing]

@notsyncing Hi. I'm the product manager of RAGFlow. Soooooo thanks for opening this PR. Supporting MCP in Agent module is on our plan. Could you send me an email at zhenhangtung@gmail.com so we can better align our vision with your work?

Sure! I have sent you a mail.