{"version":"2.1.321","anchor":"untrusted-mcp-resource-names-are-sanitized","canonical_anchor":"untrusted-mcp-resource-names-are-sanitized","heading":"Hidden characters are now stripped from MCP file names and titles","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321\/e\/untrusted-mcp-resource-names-are-sanitized","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321","markdown":"### Hidden characters are now stripped from MCP file names and titles\n\nClaude Code removes control, formatting and invisible characters from names and titles of files returned by MCP servers\n\n**What**\n\nMCP (Model Context Protocol) is the way Claude Code connects to outside tools and data sources, called MCP servers. When an MCP server returns a file, Claude Code now strips control characters, formatting characters and invisible characters from its name and title. There is also a cap on how many are handled.\n\n**Why**\n\nAn MCP server you do not fully trust could hide text in characters you cannot see. Removing them makes it harder to slip hidden instructions to Claude through a file name.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}