Expose (JSON-RPC Proxy)

title: Expose description: Easily build MCP tools for Claude desktop app

Expose lets you build MCP tools that you can invoke with MCP client like Claude desktop app.

• Self-hosted: You can easily self-host tools and deploy them on your own server.
• Unified gateway: Generates a single HTTP endpoint that you can register with expose-cli
• Flexible: Easily configure and customize your tools to fit your needs.

Getting started

1. Setup expose CLI

   curl -fsSL https://github.com/a0dotrun/expose/releases/download/stable/download_cli.sh | bash
   

2. Install dependencies

   npm i @a0dotrun/expose
   

3. Create server

   touch src/server.ts
   

   import { create } from "@a0dotrun/expose"
   
   const app = create({
     tools: [],
   })
   
   export default {
     port: 3000,
     fetch: app.fetch,
   }
   

4. Define your tools

+ import { tool } from "@a0dotrun/expose/tool"
+ import { subscription } from "@acme/lib/subscription"
+ import { z } from "zod"

+ const getCustomerSubscription = tool({
+   name: "getCustomerSubscription",
+   description: "Get subscription information for a customer",
+   args: z.object({
+       customer: z.string().uuid()
+   }),
+   run: async (input) => {
+     // Your subscription logic here
+     return input;
+   },
+ });


+ const createCustomerSubscription = tool({
+   name: "createCustomerSubscription",
+   description: "Create a subscription for a customer",
+   args: z.object({
+       customer: z.string().uuid()
+   }),
+   run: async (input) => {
+     // Your subscription logic here
+     return input;
+   },
+ });

const app = create({
  tools: [
+    getCustomerSubscription,
+    createCustomerSubscription,
  ],
});

5. Start server

   npm run dev
   

   You can also deploy the server and note down the public URL.

6. Register in Claude desktop app MACOS Claude desktop MCP config path: ~/Library/Application Support/Claude/claude_desktop_config.json

{
  ...
  "mcpServers": {
    "subscriptionManager": {
      "command": "/Users/acmeuser/.local/bin/expose-cli",
      "args": ["--url", "http://localhost:3000", "--timeout", "15"]
    }
  }
  ...
}

replace localhost with your public URL

expose is created by @_sanchitrk at a0

Acknowledgements

I was inspired by opencontrol