AI assistants (MCP)

Connect Claude, ChatGPT, your own chatbots and phone agents to the vynst MCP server, with the user's rights and approvals for sensitive actions.

vynst (inwendo ERP) includes its own MCP server (Model Context Protocol). Through it, AI assistants such as Claude, ChatGPT, Mistral Le Chat, Cursor or your own chatbots work with your data. An assistant never sees or does more than the person whose login it uses.

Endpoints

Address	For
`https://your-instance.iw-erp.de/mcp/`	signed-in users: OAuth, API token (`x-iw-jwt-token`) or session
`https://your-instance.iw-erp.de/mcp/public/`	without sign-in, only public tools such as events and news, for example for a chat on the website

The server is stateless: one JSON-RPC message per request, no sessions, no SSE. It knows server/discover, tools/list and tools/call. Tool titles and descriptions are available in German and English (?lang=en).

Connecting Claude and other assistants

With the setting mcp_oauth_discovery_enabled, the address and a login are enough:

In Claude, under Settings → Connectors → Add custom connector (Einstellungen → Connectors → Eigenen Connector hinzufügen), enter the URL https://your-instance.iw-erp.de/mcp.
Claude finds the login via /.well-known/oauth-protected-resource/mcp and /.well-known/oauth-authorization-server, registers itself as an OAuth client and redirects you to sign in.
You sign in and confirm the permission. Done.

Allowed redirect addresses are listed in mcp_oauth_registration_redirect_hosts (by default: Claude, ChatGPT, Mistral, VS Code, Cursor and the MCP proxy of vynst; localhost is always allowed, for example for Claude Code). The web server must forward /mcp/*, /oauth/* and /.well-known/oauth-* to vynst.

Trying it with an API token

curl -s https://your-instance.iw-erp.de/mcp/ \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/list' \
  -H 'x-iw-jwt-token: <TOKEN>' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientCapabilities":{}}}}'

For tools/call, also set the header Mcp-Name: <tool>.

What an assistant sees

A tool only appears when four checks pass. Otherwise, it looks to the assistant like an unknown tool:

Check	Example
Switch of the installation	`mcp_report_tools_enabled` off: no report tools
Tool filter of the API token	token may only use `crm_search_persons` and `ticket_create`
Endpoint restriction of the token	token only for `GET /api/crm/crmpeople`
The user’s rights	without read rights for contacts, no `crm_*` tools

Read, write, propose

Type	Meaning	Examples
read	changes nothing	`crm_search_persons`, `report_members`, `event_list_upcoming`
write	changes immediately, but only internal data or the user’s own data	`ticket_add_internal_note`, `self_service_update_person`
proposal	creates a request; nothing happens until a person approves it in the admin area	`membership_propose_cancel`, `notification_propose_mail`, `api_propose_patch`

Anything that cancels, bills, moves money, writes to members or changes the customer app goes through approvals. With mcp_approval_four_eyes, two people must approve. For the contribution run, SEPA and imports, the four-eyes principle is enabled by default.

Through the general api_* tools, an assistant can reach every REST endpoint. What it may change there is set by mcp_api_write_mode: approval (default, proposals only), off (read only) or direct (immediate changes).

Important settings

Setting	Default	Effect
`mcp_server_enabled`	on	MCP server under `/mcp/`
`mcp_server_public_enabled`	on	anonymous endpoint `/mcp/public/`
`mcp_oauth_discovery_enabled`	off	connecting by URL and sign-in
`mcp_api_write_mode`	`approval`	writing via the API tools
`mcp_approval_tools_enabled`	off	approval queue and all proposals
`mcp_report_tools_enabled`	off	report figures (`report_*`)
`mcp_approval_import_enabled`	off	file imports via an assistant (`import_*`)
`mcp_app_config_tools_enabled`	off	configure customer app v2 (`app_*`)
`mcp_audit_log_enabled`	on	every `tools/call` goes into the audit log, kept for 180 days

Phone assistants

AI agents on the phone verify callers with caller_verify before they give any information. Together with the general call webhook, the conversation then arrives in vynst as a call.

Importing data through an assistant

An assistant can propose a file for import (import_propose_file) and query the status (import_status). Nothing is imported until it is approved. The guide Importing data describes which files vynst understands.