Remote triggers: MCP tools fail to load and network proxy blocks outbound HTTP after initial run

Description

Remote scheduled triggers (created via both the API and the web UI at claude.ai/code/scheduled) fail silently after their initial run. MCP connector tools do not load, and the execution environment's network proxy blocks outbound HTTP to custom domains. Runs show a green checkmark ("success") despite producing no output.

Environment

• Plan: Max
• Platform: claude.ai/code/scheduled (web UI) and Claude Code CLI (RemoteTrigger API)
• Model: claude-sonnet-4-6
• MCP Connectors: Slack (mcp.slack.com), Gmail (gmail.mcp.claude.com), Google Calendar (gcal.mcp.claude.com)

Steps to Reproduce

1. Create a remote scheduled trigger with a Slack MCP connector
2. Give it a simple instruction: "Send a Slack DM to user U07FWP7TQCW with this message: 'test'"
3. Run it manually — it works on the first run (the one immediately after creation)
4. Wait for the next scheduled run, or trigger another manual run later
5. The run shows a green checkmark but produces no output

Observed Behavior

Error 1 — MCP tools not loading:
The agent reports: "No Slack MCP tools are present in this environment (no slack_post_message, slack_send_dm, or similar tools were found)."

The Slack connector is configured on the trigger but its tools are not available to the agent at runtime. This means the agent cannot post messages, send DMs, or report errors — it fails completely silently.

Error 2 — Network proxy blocks outbound HTTP:
The agent reports: 403 Forbidden (host_not_allowed) when using curl to reach ag-precon-api.netlify.app (a Netlify Functions endpoint). The execution environment's network proxy does not allow the domain.

Error 3 — False success status:
Runs that fail due to the above issues still show a green checkmark in the run history. There is no indication of failure in the UI.

Timeline

• April 3, 2026: Created 4 triggers via the RemoteTrigger API. Initial runs on creation day worked — MCP tools loaded, curl reached external APIs, Slack messages posted successfully.
• April 4–6, 2026: All subsequent scheduled and manual runs failed silently. No Slack messages, no DMs, no errors surfaced to the user. Runs show green checkmarks.
• April 6, 2026: Diagnosed the issue by clicking into run transcripts in the web UI. Created a brand new trigger from the web UI with a fresh Slack connector — same failure. MCP tools did not load.

Triggers Affected

All 4 triggers on the account exhibit this behavior:

• AG Bid Inbox Scanner (hourly, M-F) — Slack + Gmail + Google Calendar connectors
• AG Daily Pipeline Update (weekdays 8:35am) — Slack connector
• AG Bid Status Alerts (weekdays 8:30am) — Slack connector
• AG Pipeline Health Check (weekdays 8:45am) — Slack connector

Plus a newly created test trigger (from web UI, fresh Slack connector) — same failure.

Expected Behavior

• MCP connector tools should be available to the agent on every run, not just the first
• The network proxy should allow outbound HTTP to domains that worked on initial creation
• Failed runs should not show a green checkmark — they should surface errors in the UI

Workaround

Currently running the same tasks manually from a local Claude Code CLI session, where all MCP tools and outbound HTTP work correctly. The issue is isolated to the remote trigger execution environment.