feat: implement MCP Client

[longfin]

This PR adds Model Context Protocol(MCP) client feature, to enable leveraging various MCP servers.

• Due to the nature of web-based projects, I want to exclude stdio transport and only support SSE transport.
• Set the SSE endpoint as an environment variable beginning with the MCP_SSE_ prefix.
• I'm thinking about integrating the basic UI, but it would be better to handle them into other PR due to size.

Here are the details of this work I am thinking about.

• Configuration
• Toolset conversion
• LLM integration (llmcall, chat, summary)
• UI Integration
• Disabling for unsupported models
• Progress reporting
• Abort handling

Since I don't fully understand this project and its tech stack, there may be some inappropriate technology use or approaches. so, if you see anything weird, please feel free to let me know!

[longfin]

The intended works has been completed. While doing so, I wanted to add the Prompt feature, but it would be better be done in the next PR. 😅

@thecodacus Could you review this PR? 🙏

[thecodacus]

I see this relies on function calling is function calling is the only way to do this.. if so We might need to have a way to indicate the user that. and have a fallback mechanism for models that does not support function calling, and disable tool call in such scenario

[longfin]

I see this relies on function calling is function calling is the only way to do this.. if so We might need to have a way to indicate the user that. and have a fallback mechanism for models that does not support function calling, and disable tool call in such scenario

Fair enough. I'll consider them and back to here after addressing. thanks!

[chrismahoney]

I've been poking at the server and client sides of MCP over the past couple of weeks, and am re-acquainting myself with the codebase after a very busy spell, but I'm happy to help bridge the gap between what MCP is (and isn't), and some misconceptions that might arise from MCP adoption via Bolt. Still learning about where I stand regarding the webapp interacting with MCP versus a native desktop app, even though Electron and web builds aren't extremely different.

Anyway, feel free to reach out and I'll monitor this thread if there's some way I can help with testing. Got more MCP tool "servers" over here than I know what to do with and my first thought was to augment Bolt with it.

[longfin]

In addition to the feedback I received, I am implementing missing features (progress monitoring, abort signal), and I think I will be able to implement the MCP client after I have sorted out the issues related to the abort signal first.

I will submit this as a separate PR in advance. (please let me know if there are already working on or preparing for the aborting signal 🙏 )

[longfin]

In addition to the feedback I received, I am implementing missing features (progress monitoring, abort signal), and I think I will be able to implement the MCP client after I have sorted out the issues related to the abort signal first.

I will submit this as a separate PR in advance. (please let me know if there are already working on or preparing for the aborting signal 🙏 )

Opened #1538

[longfin]

Update:

• As many of you already know, MCP spec has been updated at Mar 26th. so I'm waiting for official SDK bump now.
• Also, I changed my mind that it would be better to incorporate the configuration UI work that was originally postponed into this PR. This is because handling the MCP server settings with cookies will change when and how the client is initialized.
  • 
  • Feel free to let me know about configuration if you have any though or idea too. 🙏

[xKevIsDev]

This is some nice work. I would like to note that the AI-SDK has been since updated to support MCP might be worth taking a look in to for this.

[ReEnvisionAi]

Can we look at implementing this feature in the main branch - its very important!