MCP errors and fixes
Each fix comes from a real failure in our own hands-on tests, not from guesswork.
- MCP error: "Incompatible auth server: does not support dynamic client registration"
- MCP Inspector keeps failing after a bad OAuth attempt
- Notion MCP: the consent Continue button stays disabled
- GitHub MCP issue_write shows a form and creates nothing
- MCP tool results too large: context window blown by one call
- MCP tool call times out on slow servers
- GitMCP returns "No documentation found."
- MCP error -32601 Method not found on resources/list
- MCP search returns results for nonsense queries
- Slack MCP search fails: needs keywords and natural_language_query
- Hugging Face MCP: "used anonymously and may be rate limited"
- MCP tool says "Please set your API key" on a no-signup server
- MCP server accepts calls missing a required field
- MCP error: "Error POSTing to endpoint: <!DOCTYPE html>"
- MCP URL reader returns a 404 page as a normal result
- CoinGecko MCP execute: "The code is missing a top-level run function"