MCP Dynamic Header Generation with headersHelper

What: MCP server configurations can now specify a shell command that generates HTTP headers dynamically at runtime, enabling secure credential management and token rotation.

How to use:

{
  "mcpServers": {
    "my-api": {
      "transport": {
        "type": "sse",
        "url": "https://api.example.com/sse",
        "headers": {
          "X-Static-Header": "value"
        },
        "headersHelper": "~/scripts/get-auth-token.sh"
      }
    }
  }
}

Details:

• The headersHelper command must output valid JSON with string key-value pairs
• Dynamic headers override static headers (merge strategy: {...static, ...dynamic})
• Includes workspace trust security checks for project/local-scoped servers at Xo6() at line 393477
• Comprehensive validation ensures proper JSON format and string values
• Errors are logged with telemetry event tengu_mcp_headersHelper_missing_trust
• Use cases: fetching tokens from credential managers, generating time-based auth, reading secrets from environment-specific sources