{"version":"2.1.309","anchor":"task-file-saves-and-desktop-file-reference-refusals-for-mcp","canonical_anchor":"task-file-saves-and-desktop-file-reference-refusals-for-mcp","heading":"New file handling steps for MCP tools in desktop and cowork","tier":"internal","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.309\/e\/task-file-saves-and-desktop-file-reference-refusals-for-mcp","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.309","markdown":"### New file handling steps for MCP tools in desktop and cowork\n\nMCP tools gain steps for saving task files and uploading files from a pane, and file-reference tools can now refuse when a file fill is not declared\n\n**Unclear.** It is not clear how these file steps are switched on or where a reader would see them.\n\n**What**\n\nMCP servers are outside programs that give Claude extra tools. Claude Code wraps those tools with extra steps, and several were added:\n\n- A step that saves task files, for connected servers that pass a check.\n\n- A file upload step for servers that run inside an app pane, used when Claude Code is not running remotely or in cowork.\n\n- An override that keeps one server from being allowed through by a permission bypass mode.\n\n- Tools that refer to files can now refuse with `desktop_drive_fill_not_declared` or `desktop_drive_fill_declaration_conflict`, and can have the file filled in on the host side.\n\n**Why**\n\nThese point to new work on how files move between Claude, MCP tools and the desktop and cowork apps. If an MCP tool refuses with one of the two messages above, the file it was given was not declared correctly.\n\n- Flag `tengu_mcp_strip_trailing_xml_tags`: Not enough to say (read for one account on one subscription tier against v2.1.309; this account: no value returned, anonymous baseline: no value returned, compiled default: off) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: MCP\n- Tier: Under the hood\n- Useful: 3\/5\n- Signal: 3\/5\n- Scope: individual\n- Heads-up: no"}