Exa MCP endpoint (mcp.exa.ai) timing out while REST API works

[chindris-mihai-alexandru]

Problem

The Exa MCP remote endpoint (https://mcp.exa.ai/mcp) experiences frequent timeouts and 520 Cloudflare errors when used with OpenCode, while the REST API (api.exa.ai) works without issues.

Error Messages

Timeout Error:

Request timeout after 5000ms

520 Cloudflare Error:

520: Web server returns an unknown error

Configuration Attempted

"exa": {
  "type": "remote",
  "url": "https://mcp.exa.ai/mcp?exaApiKey=...&tools=web_search_exa,deep_search_exa,get_code_context_exa"
}

Root Causes

After investigation, there appear to be two separate issues:

1. Timeout Issue (OpenCode-related)

OpenCode v1.1.1 introduced a 5000ms default timeout. The Exa MCP endpoint can take longer than 5 seconds to respond, causing timeout errors.

Fix: Add "timeout": 31000 to the config

2. 520 Cloudflare Error (Exa infrastructure issue)

The 520 error is a Cloudflare error meaning "web server returns an unknown error" - this occurs when Exa's origin server (behind Cloudflare) returns an empty or unexpected response.

Reference: https://developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-5xx-errors/error-520/

Status: Exa team investigated and resolved this issue on January 5, 2026.

Workarounds

Option 1: Add timeout (for timeout issues)

"exa": {
  "type": "remote",
  "timeout": 31000,
  "url": "https://mcp.exa.ai/mcp?exaApiKey=..."
}

Option 2: Use local MCP server (recommended for reliability)

"exa": {
  "type": "local",
  "command": ["npx", "-y", "exa-mcp-server"],
  "timeout": 60000,
  "environment": {
    "EXA_API_KEY": "your-api-key"
  }
}

The local server uses the REST API (api.exa.ai) directly, which is more stable than the remote MCP endpoint.

Related Issues

• exa-labs/exa-mcp-server#86 - HTTP SSE Endpoint issues with remote MCP
• code-yeongyu/oh-my-opencode#493 - websearch_exa timeout

Status

• Timeout issue: Resolved with config changes (add timeout parameter)
• 520 Cloudflare errors: Fixed by Exa on January 5, 2026
• Recommended approach: Use local MCP server for best reliability