Anthropic feedback: custom MCP connectors not usable in Claude Code routines

Date: 2026-05-28 Account: Ello van Gelderen ([email protected]) Component: Claude Code routines + custom MCP connectors

TL;DR

Custom MCP connectors registered at claude.ai/customize/connectors work perfectly in chat sessions but cannot be attached to scheduled routines because:

1. The /v1/code/triggers API requires a connector_uuid for mcp_connections
2. There is no API or UI surface to discover the UUID of a custom connector
3. The /schedule skill in Claude Code only lists built-in connectors (Gmail, Drive, Calendar)
4. Documentation does not address routines × custom-MCP interaction

Either this should be supported (with discoverable UUIDs) or explicitly documented as not-supported with a recommended workaround.

Reproduction

Setup

1. Deploy a custom MCP server at https://mcp.inodus.nl/mcp (FastMCP 3.x, streamable HTTP, authless)
2. Add as custom connector at claude.ai/customize/connectors → "Inodus Factory"
3. Verify chat works: open new Claude.ai chat, invoke a tool from this connector → ✅ works, "Loaded tools, used Inodus Factory integration"
4. Verify direct MCP works: connect via fastmcp Python client to the same URL → ✅ full protocol works, all 8 tools callable

Failure path

Attach connector to a scheduled routine via API:

POST /v1/code/triggers/{id}
{
  "mcp_connections": [{
    "name": "Inodus-Factory",
    "url": "https://mcp.inodus.nl/mcp"
  }]
}

→ HTTP 400: "mcp_connections.0.connector_uuid: Field required"

Workaround attempt 1: Use zero-UUID

{
  "mcp_connections": [{
    "connector_uuid": "00000000-0000-0000-0000-000000000000",
    "name": "Inodus-Factory",
    "url": "https://mcp.inodus.nl/mcp"
  }]
}

→ HTTP 200 (API accepts), but runtime: the routine does not connect to the MCP. No POST /mcp requests reach mcp.inodus.nl during the routine run. Same routine in chat-mode works fine — proving the network path is OK.

Workaround attempt 2: Discover UUID

• /schedule skill returns only 3 built-in connectors (Gmail/Drive/Calendar), even after the custom connector is added
• claude.ai/customize/connectors UI: connector tile has no visible UUID
• No documented /v1/connectors or similar API endpoint to enumerate user-attached MCPs

Impact

For our use-case (a daily-incidents-summary cloud routine that reads from our monitoring DB and emails a digest), we cannot use the MCP-connector path even though:

• The MCP server is built and deployed
• Connector is registered
• Chat usage works end-to-end
• A direct script (FastMCP client) works end-to-end

The only currently-available paths are:

1. Use chat manually each morning instead of an automatic routine
2. Build a separate non-MCP cron (e.g. local Mac Mini or separate Railway service) that bypasses the cloud-routine egress-block
3. Wait for either API support or documentation

Suggested fixes (any one would unblock this use-case)

1. /v1/connectors enumeration endpoint that lists the calling user's MCPs (built-in + custom) with their connector_uuids
2. Make connector_uuid optional when url is provided — server-side matches against the user's registered connectors by URL
3. Allow custom connectors in routines by URL alone (no UUID required), with a documented security boundary (e.g. "only URLs matching one of the user's registered connectors are accepted")
4. Documentation in https://claude.com/docs/llms-full.txt explicitly stating either "custom connectors are supported in routines via X" or "custom connectors are not yet supported in routines, use built-in connectors only"

Environment

• Claude Code: latest, plugin mode in CLI
• claude.ai web: standard, custom connector flow
• MCP server: FastMCP 3.3.1 / Python 3.13
• MCP transport: streamable HTTP (mcp.inodus.nl/mcp)
• MCP auth: authless (custom connectors don't yet support OAuth in our setup)
• Trigger API: https://api.anthropic.com/v1/code/triggers (via Claude Code RemoteTrigger tool)
• Trigger ID where this was tested: trig_017VcsBprnZFqney3qxYcowU

How to submit

Pick one:

• GitHub Issues: https://github.com/anthropics/claude-code/issues (preferred for surfacing publicly)
• Email [email protected] (per the connector docs)
• Both (publicly trackable + direct visibility for the MCP team)