npm error could not determine executable to run (exa-mcp-server)

Fix npm error could not determine executable to run for exa-mcp-server

TL;DR

Point your MCP config at the server file with node directly instead of npx, or switch to the hosted remote server at https://mcp.exa.ai/mcp. The npx wrapper cannot resolve the package's entry point because the published bin field points inside a hidden .smithery directory, which npm refuses to execute.

The exact error:

npm error could not determine executable to run

Steps

1. Confirm this is the error

Run the package by hand in a terminal:

npx -y exa-mcp-server

Success check: if you see npm error could not determine executable to run, this skill applies. If instead you see a missing API key error, that is a different problem.

2. Find where npm installed the package

npm root -g

Success check: it prints a directory. Append /exa-mcp-server/.smithery/stdio/index.cjs to it. Verify the file exists:

ls "$(npm root -g)/exa-mcp-server/.smithery/stdio/index.cjs"

3. Point the MCP config at node directly

Edit claude_desktop_config.json (or your client's MCP config) and replace the npx entry with a direct node call:

{
  "mcpServers": {
    "exa": {
      "command": "node",
      "args": ["[global npm root]/exa-mcp-server/.smithery/stdio/index.cjs"],
      "env": { "EXA_API_KEY": "[your Exa API key]" }
    }
  }
}

Success check: save the file, fully restart the client. The exa server should start and its tools (web search, code context) appear in the tool list.

4. Alternative: use the hosted remote server instead

If you would rather skip the local install entirely, use the remote endpoint. For Claude Code:

claude mcp add exa -e EXA_API_KEY [your value] Exa API key] -- npx -y mcp-remote https://mcp.exa.ai/mcp

Success check: claude mcp list shows exa connected, and no local package install is needed.

When this applies

• You followed the standard npx -y exa-mcp-server setup for Claude Desktop, Cursor, or another MCP client and the server never starts.
• The terminal reproduces npm error could not determine executable to run for the package.

When it does not apply

• You get EXA_API_KEY environment variable is not set instead. That is an auth problem: put your key in the env block.
• You are using the remote https://mcp.exa.ai/mcp URL already. Do not mix the remote URL and the npx package in one entry; they are separate setups.

Tool compatibility

• exa-mcp-server npm package, versions publishing the .smithery/stdio/index.cjs layout
• npx / npm (Node.js 18+)
• Claude Desktop, Claude Code, Cursor, KiloCode

Why it happens

The published package's bin field points at .smithery/stdio/index.cjs, a path inside a hidden dot-directory. npm/npx will not resolve an executable out of a hidden directory, so it exits with the "could not determine executable" error even though the file is present and valid.

Edge cases

• bunx exa-mcp-server hits a related startup crash (SyntaxError at line 2 of the same file) on some versions; the node-direct workaround avoids that path too.
• If npm installed the package in a user-local prefix (.npm-global), the args path must use that prefix, not the system one. npm root -g tells you which.
• Some users report success pinning an older package version (e.g. [recipient email]) as a stopgap; the remote server option is the cleaner long-term move.