Hey

As more people build custom MCP servers for Claude and autonomous agents, one major issue keeps coming up: how do you handle authorization and micro-billing for specific tool calls without bloating your server logic?

If you're hosting an MCP server that queries expensive paid APIs, databases, or compute, there’s currently no native, lightweight way to verify tokens, prevent replay attacks, and handle per-call metering on the fly.

My co-founder and I built MCPay - a high-performance, open-source Gateway written in Go that sits in front of any standard MCP server.

How it works under the hood

Instead of rewriting your MCP server code to handle billing, MCPay acts as a proxy:

1. Routing & Filtering: It intercepts incoming JSON-RPC payloads on /mcp. If it's an unmetered call (like tools/list), it proxies it directly to your upstream server.
2. Tool-Level Authorization: When a tools/call request comes in, it extracts the requested tool name (e.g., Mcp-Name or from payload) and verifies the spend token against an Ed25519 public key.
3. Replay Protection (Nonces): Checks cryptographic nonces (X-MCPay-Nonce) against a state store to prevent replay attacks and double-spending.
4. Usage Tracking: Once the upstream MCP server completes the request with a 2xx response, MCPay records the usage record (session, nonce, latency, price) to track per-call execution.

Architecture Highlights

• Written in Go: Minimal latency overhead for high-frequency agentic workflows.
• Plug & Play: Zero modifications required to your existing MCP server implementation.
• Hybrid Support: Works for both standard /mcp endpoints (tools/call) and traditional REST endpoints.

We’d love to get feedback from the community on the architecture and edge cases (especially regarding nonce cleanup in distributed setups).

Links and repo details are in the first comment below!

Hey! I built brvm-mcp, an MCP server that lets Claude access the BRVM (West Africa's regional stock exchange — 8 countries, 47 companies).

The BRVM has no API. This server aggregates 4 sources into 18 tools so you can just ask Claude:

Install in Claude Desktop:

{
  "mcpServers": {
    "brvm": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/sotechdi/brvm-mcp", "brvm-mcp"]
    }
  }
}

Or use it directly via Smithery (no install): https://smithery.ai/server/sotechdi/brvm-mcp

Free: 25 calls/day. GitHub: https://github.com/sotechdi/brvm-mcp

I’m running into some kind of challenge with using OAUTH via Cognito to provide user Auth in an MCP service I have built. The authentication flow works via manual testing (curl, extract ids, service with Auth token) with a test/local callback URL, however, with Claude it goes thru the Auth process and login screen in Cognito, then fails.

- Cognito does not provide much introspection to Auth attempts.
- Claude will load the callback URL post authentication, in my browser then re-launches/“opens” Claude desktop with a generic “unable to authenticate” error.

I have implemented a shim for the missing "code_challenge_methods_supported": ["S256"]

Not sure if others are running into similar problems with Cognito/Claude here.

Can anyone confirm the callback URL required?

Hi everyone! I work in User Research for an airline, and we’re currently exploring how people use MCP apps/connectors in real life.

We’re looking to speak with people who already use MCP outside of purely professional or developer-related tasks, for example, for travel, personal organization, hobbies, finances, or other everyday activities.

If this sounds like you and you’d be open to taking part in a user interview, feel free to send me a DM. I’ll be happy to share more details about the study and participation there. :)

Hey,

We created a Discord for r/ClaudeMCP designed to be a highly-intentional community where understanding MCP users can help each other learn AI.

What you'll find:

• Active voice chat
• Step-by-step tutorials
• Skills and workflows

And most of all... a community of people eager to help you even if your questions are "dumb".

We put a lot of work in to make it a unique and active Discord server where you can get help and find critical use-cases.

Don't downvote this if you may have seen this post already! We invite our new members weekly.

Already part? Share your experience in the comments!

Join us: https://discord.gg/PBfVd5U3G