{"version":"2.1.293","anchor":"mcp-connect-and-tool-listing-now-async-chunked-http-refuses","canonical_anchor":"mcp-connect-and-tool-listing-now-async-chunked-http-refuses","heading":"MCP responses from tool containers with a Content-Encoding are refused","tier":"notice","area":"MCP","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.293\/e\/mcp-connect-and-tool-listing-now-async-chunked-http-refuses","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.293","markdown":"### MCP responses from tool containers with a Content-Encoding are refused\n\nClaude Code now rejects compressed responses from MCP servers in tool containers, and MCP connect and tool listing were reworked\n\n**Unclear.** It is not clear what the new encoding option changes for a given server.\n\n**What**\n\nThe code that sends MCP requests over HTTP takes a new `refusesCodings` option. MCP servers are outside programs that give Claude extra tools. When the option is set and a response has any `Content-Encoding`, meaning it arrives compressed or otherwise encoded, Claude Code cancels it unread and raises an error. The error says the server sent a response with a Content-Encoding, and that Claude Code reads none from a tool container. Before, only the `br` and `zstd` encodings were refused.\n\nRelated changes in the same code:\n\n- The connect function takes an extra argument, which it passes to the proxy and sign-in wrappers.\n\n- Processing of MCP tool schemas now waits on a helper that works in batches.\n\n**Why**\n\nThis is a hardening step for MCP servers running in tool containers. A server that compresses its replies will now fail to connect instead of being read.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 3\/5\n- Scope: individual\n- Heads-up: yes"}