{"version":"2.1.242","anchor":"new-tool-host-result-system-message-in-stream-json-output","canonical_anchor":"new-tool-host-result-system-message-in-stream-json-output","heading":"New tool_host_result system message in stream-json output","tier":"use","area":"Agents","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.242\/e\/new-tool-host-result-system-message-in-stream-json-output","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.242","markdown":"### New `tool_host_result` system message in stream-json output\n\nTool host output arrives as its own system message in stream-json, easier to script against.\n\n**What**\n\nOutput from a tool host (a separate process that runs a tool on Claude Code's behalf) now arrives as its own system message in `--output-format stream-json`, so scripts can read it directly instead of parsing it out of an attachment.\n\n**Details**\n\n- The message carries the `tool_use_id`, the host name and its working directory, an optional disposition and label, an `unverified` flag, and the output lines.\n- No flag gates it; it is emitted whenever the underlying attachment appears.\n\n**Evidence**\n\n`tool_host_result`\n\n- Area: Agents\n- Names: `--output-format stream-json`\n- Tier: Use it now\n- Useful: 3\/5\n- Signal: 3\/5"}