{"version":"2.1.317","anchor":"mcp-protocol-zod-schemas-are-now-built-lazily","canonical_anchor":"mcp-protocol-zod-schemas-are-now-built-lazily","heading":"MCP message formats are now prepared only when first needed","tier":"internal","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.317\/e\/mcp-protocol-zod-schemas-are-now-built-lazily","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.317","markdown":"### MCP message formats are now prepared only when first needed\n\nClaude Code now builds the definitions it uses to check MCP messages the first time each one is used, rather than all at startup\n\n**What**\n\nMCP (Model Context Protocol) is the standard Claude Code uses to talk to outside tools and servers. Claude Code checks MCP messages against definitions of their expected format. Many of those definitions are now built the first time each one is used, instead of all at once when Claude Code starts.\n\n**Why**\n\nLess work happens at launch, so Claude Code should start somewhat faster.\n\n- Area: MCP\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 0\/5\n- Scope: individual\n- Heads-up: no"}