{"version":"2.1.280","anchor":"mcp-required-missing-agent-spawn-errors-now-carry-structured","canonical_anchor":"mcp-required-missing-agent-spawn-errors-now-carry-structured","heading":"MCP-required-missing agent spawn errors now carry structured data","tier":"internal","area":"Plugins","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.280\/e\/mcp-required-missing-agent-spawn-errors-now-carry-structured","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.280","markdown":"### MCP-required-missing agent spawn errors now carry structured data\n\nErrors for missing required MCP servers during agent spawning now include structured error data, not just a text message\n\n**What**\n\nWhen a plugin's `agent.spawn` hook tries to launch an agent that needs one or more MCP servers (external tool integrations) that aren't configured, Claude Code throws an error. That error now carries structured metadata alongside its existing text message, including a `kind` field set to `mcp_required_missing` and a `servers` field listing which servers were missing.\n\n**Why**\n\nThis makes it possible for tooling around Claude Code to detect and handle this specific failure programmatically, rather than having to parse the error's text message to figure out what went wrong and which servers need to be configured.\n\n- Area: Plugins\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 1\/5"}