Exa MCP server returns HTTP 400 on remote setup (Smithery / mcp-remote)

Question

I have an Exa MCP server (exa-mcp-server) that works locally in Claude Code, but both remote setups — Smithery and mcp-remote — fail in Claude Desktop with "Request failed with status code 400" on every Exa search. Is the remote endpoint broken, and what is the current working configuration?

Originally asked on GitHub: https://github.com/exa-labs/exa-mcp-server/issues/36

AgentArmorHQ team · Accepted Answer

**Status: fixed.** A maintainer confirmed on 2025-11-06 that Exa MCP is now fixed (npm package latest is 3.0.8) and posted updated configurations. The thread does not explain what caused the original 400 errors.

Using the npm package:

```json
{
  "mcpServers": {
    "exa": {
      "command": "npx",
      "args": [
        "-y",
        "exa-mcp-server",
        "tools=get_code_context_exa,web_search_exa,company_research_exa,crawling_exa,linkedin_search_exa,deep_researcher_start,deep_researcher_check"
      ],
      "env": {
        "EXA_API_KEY": "your-api-key-here"
      }
    }
  }
}
```

Using the remote MCP endpoint directly (no mcp-remote wrapper):

```json
{
  "mcpServers": {
    "exa": {
      "type": "http",
      "url": "https://mcp.exa.ai/mcp?tools=web_search_exa,get_code_context_exa,crawling_exa,company_research_exa,linkedin_search_exa,deep_researcher_start,deep_researcher_check",
      "headers": {}
    }
  }
}
```

The original issue's working local config used a different tool list (`web_search_exa,research_paper_search,twitter_search,company_research,crawling,competitor_finder,linkedin_search`); the maintainer's updated configs use the 7 tools shown above, and the README was updated as well.

Security note: the remote HTTP option embeds your `EXA_API_KEY` in the URL query string, so keep that config out of shared repositories.

AgentArmorHQ team · Answer

**What a GitHub user tried on GitHub** (Worked)

Ran the locally built server in Claude Code via `npx /Users/louisdilello/Dropbox/FCPS/Dev/_active_mcp_servers/exa-mcp-server/build/index.js` with a `--tools` flag listing 7 tools and `EXA_API_KEY` in the `env` block. The issue author marked this configuration as working.

Source: https://github.com/exa-labs/exa-mcp-server/issues/36

AgentArmorHQ team · Answer

**What a GitHub user tried on GitHub** (Didn't work)

In Claude Desktop, configured Exa through Smithery with `npx -y @smithery/cli@latest run exa --key [KEY]`. Every Exa search returned `Request failed with status code 400`.

Source: https://github.com/exa-labs/exa-mcp-server/issues/36

AgentArmorHQ team · Answer

**What a GitHub user tried on GitHub** (Didn't work)

In Claude Desktop, configured Exa manually with `npx -y mcp-remote https://mcp.exa.ai/mcp?exaApiKey=[KEY]`. Same HTTP 400 error on all search requests.

Source: https://github.com/exa-labs/exa-mcp-server/issues/36

AgentArmorHQ team · Answer

**What @iFredOS tried on GitHub** (Partly worked)

Removed the Exa MCP server from Claude Code and re-added it. One "test" search succeeded, but a minute later the 400 error returned; the user reported it had previously worked for about two weeks.

Source: https://github.com/exa-labs/exa-mcp-server/issues/36#issuecomment-3235211926

Exa MCP server returns HTTP 400 on remote setup (Smithery / mcp-remote)

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Exa MCP server returns HTTP 400 on remote setup (Smithery / mcp-remote)

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