MRT Log Tools

MCP tools for tailing real-time application logs from a Managed Runtime (MRT) environment over a WebSocket. Use them to watch SSR/server output while you reproduce a request, verify a deployment, or investigate an error on PWA Kit and Storefront Next storefronts. Available in the DIAGNOSTICS, PWAV3, and STOREFRONTNEXT toolsets.

MRT logs are always a live stream — there is no historical fetch and no log files to list (unlike the SFCC instance log tools). The workflow is therefore watch-only: start a watch, drain it with poll, then stop.

Authentication

All MRT log tools require MRT API authentication (the same credentials as mrt_bundle_push).

Required:

• MRT API key — from --api-key, the MRT_API_KEY environment variable, or ~/.mobify.
• Project — from --project / -p, MRT_PROJECT, or mrtProject in dw.json.
• Environment — from --environment / -e, MRT_ENVIRONMENT, or mrtEnvironment in dw.json.

Optional:

• Cloud origin — from --cloud-origin, MRT_CLOUD_ORIGIN, or mrtOrigin in dw.json (defaults to https://cloud.mobify.com).

mrt_logs_watch_poll, mrt_logs_watch_stop, and mrt_logs_watch_list operate on server-side state only and do not require fresh credentials per call.

See Configuration for credential setup.

Recovery from orphaned watches

Log watches are stateful and live in the MCP server process. Only one watch is allowed per project/environment/origin. If an agent loses track of an active watch:

1. List active watches — call mrt_logs_watch_list (no args). It returns all watches with their watch_id, project, environment, and buffered counts.
2. Stop orphaned watches — call mrt_logs_watch_stop with the watch_id to close the underlying WebSocket.
3. Idle cleanup — watches inactive for 30 minutes are automatically destroyed.
4. Restart the MCP server — last resort; destroys all watch state.

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Watch lifecycle

mrt_logs_watch_start

Start a background tail of the configured MRT environment's logs. Returns a watch_id immediately and buffers entries in memory until mrt_logs_watch_poll drains them.

Workflow: call mrt_logs_watch_start before triggering the request or SSR action you want to capture. Because MRT logs are a live stream, anything emitted before the watch connects is not captured.

Parameter	Type	Required	Default	Description
level	string[]	No		Drop entries not matching these levels (ERROR, WARN, INFO, DEBUG, ...) before buffering. Case-insensitive.
search	string	No		Drop entries not matching this case-insensitive substring (against message and raw) before buffering.

Project and environment are taken from configuration (flags / env vars / dw.json), not tool parameters.

Returns: {watch_id, project, environment, started_at}.

The CLI b2c mrt tail-logs --search treats the pattern as a regex; this MCP tool uses a simpler, safer case-insensitive substring match for search.

mrt_logs_watch_poll

Drain buffered entries. If the buffer is empty, blocks up to timeout_ms waiting for new entries. Returns immediately if entries are already buffered or the stream has stopped.

Parameter	Type	Required	Default	Description
watch_id	string	Yes		Watch id from mrt_logs_watch_start
timeout_ms	number	No	5000	Max time to block when buffer is empty. 0 returns immediately.
max_entries	number	No	200	Maximum entries returned per call

Returns: {watch_id, entries, errors, truncated, buffered_remaining, dropped_entries, stopped}. When truncated is true, call again to drain the rest.

• entries: [{timestamp, requestId, shortRequestId, level, message, raw}] — parsed MRT log entries buffered since the last poll. requestId/level/timestamp are present when the line can be parsed; message and raw are always present.
• errors: [{message, at}] where at is an ISO 8601 timestamp of when the WebSocket error occurred.
• dropped_entries: count of entries evicted (buffer cap) since the last poll; resets to 0 after each poll.
• stopped: true once the WebSocket has closed — whether via mrt_logs_watch_stop, an idle/server timeout, or a connection failure. When stopped is true, check errors for the reason and start a new watch to resume.

mrt_logs_watch_stop

Stop a watch and close its WebSocket. Idempotent — stopping an already-stopped watch returns success.

Parameter	Type	Required	Description
watch_id	string	Yes	Watch id from mrt_logs_watch_start

Returns: {watch_id, stopped_at, total_entries_seen}.

mrt_logs_watch_list

List active watches. Use to recover orphaned watches or inspect buffered counts.

No parameters.

Returns: {watches: [{watch_id, project, environment, origin, buffered_entries, total_entries_seen, dropped_entries, stopped, created_at, last_activity_at}]}.

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See also

• SFCC instance log tools — logs_watch_* for B2C Commerce instance logs via WebDAV
• mrt_bundle_push — build and deploy MRT bundles
• MRT CLI commands — b2c mrt tail-logs and the rest of the b2c mrt command tree