Comment by joshstrange 3 days ago
Very cool. Like I said I can make it work with Stdio but I have a SSE MCP proxy I wrote to combine multiple MCP servers (just to make plugging in all my tools to a new client easier to test). That said, I think after looking at the docs that I'll be tempted to move my tools in directly but I probably will keep them behind MCP for portability.
I have used `mcp-proxy` but (afaik) you can only use it 1-to-1 and I wanted an N-to-1 proxy so that instead of configuring all my MCP servers in the multiple clients I've tested out I could just add 1 server and pull in everything.
I found `mcp-proxy-server` [0] which seemed like it would do what I want but I ran into multiple problems. I added some minor debug logging to it and the ball sort of rolled downhill from there. Now it's more my code than what was there originally but I have tool proxying working for multiple clients (respecting sessionIds, etc) and I think I've solved most all the issues I've run into and added features like optional tool prefixing so there isn't overlap between MCP servers.
Given what I know now, I don't think N-to-1 is quite as useful as I thought. Or rather, it really depends on your "client". If you can toggle on/off tools in your client then it's not a big problem but sometimes you don't want "all" the tools and if you client only allows toggling per MCP server then you will have an issue.
I love the ideas of workflows and how you have defined agents. I think my current issue is almost too many tools and the LLM sometimes gets confused over which ones to use. I'm especially thrilled with your HTTP endpoints you expose for the agents. My main MCP server (my custom tools I wrote, vs the third-party ones) exposes an HTTP GUI for calling the tools (faster iteration vs trying it through LLMs) and I've been using that and 3rd-party chat clients (LibreChat and OpenWebUI) as my "LLM testing" platform (because I wasn't aware of a better options) but neither of those tools let you "re-expose" the agents via an API.
All in all I'm coming to the conclusion that 90% of MCP servers out there are really cool for seeing what's possible but it's probably best to write your own tools/MCP since most all MCP servers are just thin wrappers around an API. Also it's so easy to create an MCP server that they are popping up all over the place and often of low quality (don't fully implement the API, take shortcuts for the authors use-case, etc). Using LLMs to writing the "glue" code from API->Tool is fairly minor and I think is worth "owning". To sum that all up: I think my usage of 3rd party MCP servers is going to trend towards 0 as I "assimilate" MCP servers into my own codebase for more control but I really like MCP as a way to vend tools to various different LLM clients/tools.
Thanks for sharing! It's so helpful to hear real world experiences like this. Would you be interested in meeting up on a call sometime? I'd love to chat about how you're using MCP to help inform how we can make all of this easier for folks. We're actively thinking about our APIs for tool use and MCP right now.
I appreciate the offer but I think you'll probably find someone better to talk to here in the comments.
MCP is super cool and I've loved playing with it but playing with it is all I'm doing. I'm working on some tools to use in my $dayJob and also just using it as an excuse to learn about LLMs and play with new tech. Most my work is writing tools that connect our to our distributed fleet of servers to collect data, run commands, etc. My goal is to build a SlackOps-type bot that can provide extra context about errors we get in Slack (Pull the latest commits/PRs around that code, link to current deployed version, provide all the logs for the request that threw an error, check system stats, etc). And while I have tools written to do all of that I'm still working on bringing it all together in something more than a bot I can invoke from Slack and make MCP calls.
All that to say, I'm not a professional user of MCP/Mastra and my opinion is probably not one you want shaping your framework.
No worries! But I am definitely interested in chatting still - that you've tried it in multiple ways, ran into pain points, and overcame those in your own ways is super interesting and valuable. Playing around is how everyone starts and this "agents with tool use in prod" game is still very new. These APIs should work well and make sense for folks who are just getting into it as well folks who have been around the block. If you change your mind let me know! Would love to chat
Oh nice, did you write your own proxy or are you using something like https://www.npmjs.com/package/mcp-proxy ?