gemini-cli - 💡(How to fix) Fix MCP server discovery failure: ByteString conversion error when using non-ASCII characters in headers [1 participants]

It appears that Gemini CLI attempts to convert these header values into a ByteString (restricted to 255), causing an overflow error when a Unicode character is encountered.

TL;DR

The MCP server discovery process can be fixed by ensuring configuration headers only contain ASCII characters or by properly handling Unicode characters in the ByteString conversion.

Guidance

• Verify that the issue is indeed caused by non-ASCII characters in the configuration headers by testing with ASCII-only headers.
• Consider updating the Gemini CLI to handle Unicode characters correctly, potentially by using a more suitable data type than ByteString.
• As a temporary workaround, avoid using non-ASCII characters in configuration headers.
• Test the discovery process with a modified settings.json file that contains only ASCII characters in the headers.

Example

"mcpServers": {
		"mcp": {
			"httpUrl": "https://mcp",
			"headers": {
				"X-Custom": "maka",
			},
			"timeout": 60000
		},

Notes

The provided information does not specify how the Gemini CLI handles Unicode characters, so a definitive fix may require additional details about the CLI's implementation.

Recommendation

Apply workaround: Avoid using non-ASCII characters in configuration headers, as this is a simple and effective way to prevent the overflow error until a more robust solution is available.