{"version":"2.1.311","anchor":"mcp-structuredcontent-can-arrive-base64-wrapped-and-is-omitt","canonical_anchor":"mcp-structuredcontent-can-arrive-base64-wrapped-and-is-omitt","heading":"MCP servers can send structured results in an encoded form","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.311\/e\/mcp-structuredcontent-can-arrive-base64-wrapped-and-is-omitt","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.311","markdown":"### MCP servers can send structured results in an encoded form\n\nClaude Code can now decode MCP structured results sent under the claude\/structuredContentJsonBase64 key and show them as JSON text\n\n**Unclear.** The switch that controls the decoding was not identified, so it is unclear whether it is active for you.\n\n**What**\n\nMCP servers are outside programs that give Claude Code extra tools. A tool can return structured content, which is data in a fixed shape. Claude Code now handles a new form of it:\n\n- when a result's structured content holds only the key `claude\/structuredContentJsonBase64`, Claude Code decodes it into JSON text, behind a switch\n\n- image results from an MCP tool can now be passed through a separate image-reading step\n\n- reading a folder from an MCP server can now be cancelled partway\n\nClaude Code also reports an error when it tries to read a folder from a server that does not offer folder reading.\n\n**Why**\n\nMCP servers get another way to send structured results, which Claude can then read as plain JSON text.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: no"}