How to run MCP inspector with TypeScript SDK servers?

[atroyn]

I have the quickstart index.ts :

import { McpServer, ResourceTemplate } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";

const server = new McpServer({
  name: "Echo",
  version: "1.0.0"
});

server.resource(
  "echo",
  new ResourceTemplate("echo://{message}", { list: undefined }),
  async (uri, { message }) => ({
    contents: [{
      uri: uri.href,
      text: `Resource echo: ${message}`
    }]
  })
);

server.tool(
  "echo",
  { message: z.string() },
  async ({ message }) => ({
    content: [{ type: "text", text: `Tool echo: ${message}` }]
  })
);

Dependencies installed.

I attempt to invoke the MCP inspector (https://modelcontextprotocol.io/docs/tools/inspector) to make sure my server is working as expected.

I run npx @modelcontextprotocol/inspector npm run -s start (s to suppress the startup logging)

The inspector starts up but not in a connected state:

When I hit connect I get no UI change, and the following on the terminal:

New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'npm',
  args: 'run -s start',
  env: '{"HOME":"/Users/antontroynikov","LOGNAME":"antontroynikov","PATH":"/Users/antontroynikov/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/mcp/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/node_modules/.bin:/Users/antontroynikov/Projects/node_modules/.bin:/Users/antontroynikov/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/share/dotnet:/usr/local/go/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/Users/antontroynikov/miniforge3/condabin:/Users/antontroynikov/.cargo/bin:/Users/antontroynikov/.orbstack/bin:/Users/antontroynikov/.orbstack/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"antontroynikov"}'
}
Stdio transport: command=/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/bin/npm-cli.js, args=run,-s,start, env={"HOME":"/Users/antontroynikov","LOGNAME":"antontroynikov","PATH":"/Users/antontroynikov/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/mcp/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/node_modules/.bin:/Users/antontroynikov/Projects/node_modules/.bin:/Users/antontroynikov/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/share/dotnet:/usr/local/go/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/Users/antontroynikov/miniforge3/condabin:/Users/antontroynikov/.cargo/bin:/Users/antontroynikov/.orbstack/bin:/Users/antontroynikov/.orbstack/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"antontroynikov"}
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
Received message for sessionId ae63680c-3a7f-4b03-8ffb-ac6f1b93e341
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'npm',
  args: 'run -s start',
  env: '{"HOME":"/Users/antontroynikov","LOGNAME":"antontroynikov","PATH":"/Users/antontroynikov/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/mcp/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/node_modules/.bin:/Users/antontroynikov/Projects/node_modules/.bin:/Users/antontroynikov/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/share/dotnet:/usr/local/go/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/Users/antontroynikov/miniforge3/condabin:/Users/antontroynikov/.cargo/bin:/Users/antontroynikov/.orbstack/bin:/Users/antontroynikov/.orbstack/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"antontroynikov"}'
}
Stdio transport: command=/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/bin/npm-cli.js, args=run,-s,start, env={"HOME":"/Users/antontroynikov","LOGNAME":"antontroynikov","PATH":"/Users/antontroynikov/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/mcp/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/panopticon/node_modules/.bin:/Users/antontroynikov/Projects/CascadeProjects/node_modules/.bin:/Users/antontroynikov/Projects/node_modules/.bin:/Users/antontroynikov/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/antontroynikov/.nvm/versions/node/v20.18.1/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/share/dotnet:/usr/local/go/bin:/Users/antontroynikov/.nvm/versions/node/v16.15.0/bin:/Users/antontroynikov/.codeium/windsurf/bin:/Users/antontroynikov/.opam/default/bin:/Users/antontroynikov/miniforge3/condabin:/Users/antontroynikov/.cargo/bin:/Users/antontroynikov/.orbstack/bin:/Users/antontroynikov/.orbstack/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"antontroynikov"}
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection

This then appears to loop. How do I use this tool with the TypeScript server to make sure my server is working correctly?

[atroyn]

As a new user of the SDK, this has been a pretty frustrating experience so far.

[atroyn]

these sections of the README appear to be missing:

Running Your Server
Development Mode
Claude Desktop Integration
Direct Execution

[atroyn]

Spent time digging around, it seems the right way to do this is to add

import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

...

const transport = new StdioServerTransport();
await server.connect(transport);

So that the server actually connects to a transport that the client (in this case, MCP inspector) can access.

Strongly suggest adding this to the examples to make this guide much more self-contained.

[jspahrsummers]

Sorry, this README has been in flux since the API changes. Agree with your points! Will land some basic changes to make the end-to-end setup more obvious, but need to follow up with even easier tooling too.