MCP Tester

Test any MCP server - discover tools and call them interactively.

1. Enter any MCP server URL
2. Discover available tools via the MCP protocol
3. Call tools with custom arguments
4. See raw JSON-RPC responses

Visit the main.ts endpoint and enter an MCP server URL to test.

# Get the endpoint URL from main.ts, then:

# Discover tools
curl -X POST "YOUR_ENDPOINT/?url=https://dicemcp.val.run" \
  -H "Content-Type: application/json" \
  -d '{"method": "discover"}'

# Call a tool
curl -X POST "YOUR_ENDPOINT/?url=https://dicemcp.val.run" \
  -H "Content-Type: application/json" \
  -d '{"method": "call", "tool": "roll_dice", "args": {"count": 3}}'

# Quick connectivity test
curl "YOUR_ENDPOINT/api/test?url=https://dicemcp.val.run"

// Get endpoint URL from main.ts file details
const TESTER = "https://your-endpoint.web.val.run";
const MCP_URL = "https://your-mcp.val.run";

// Discover tools
const discovery = await fetch(`${TESTER}/?url=${encodeURIComponent(MCP_URL)}`, {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ method: "discover" }),
}).then(r => r.json());

console.log(discovery.tools);

// Call a tool
const result = await fetch(`${TESTER}/?url=${encodeURIComponent(MCP_URL)}`, {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ 
    method: "call", 
    tool: "your_tool_name", 
    args: { foo: "bar" } 
  }),
}).then(r => r.json());

console.log(result);

The test.ts file demonstrates testing the dice MCP server. Run it from the Val Town UI to verify everything works.

• mcp-dice - Minimal MCP server example
• MCP Specification