deltat — Claude Code MCP server: booking and setup
deltat gives an agent a calendar flow built around slot search, temporary holds, and atomic confirmation. It helps avoid double bookings.
claude mcp add --env DELTAT_PASSWORD=<DELTAT_PASSWORD> --env DELTAT_HOST=<DELTAT_HOST> --env DELTAT_PORT=<DELTAT_PORT> --env DELTAT_DATABASE=<DELTAT_DATABASE> --env DELTAT_USER=<DELTAT_USER> --transport stdio mcp -- npx -y @open-deltat/mcpWhat deltat does
deltat exposes calendar actions through find_slots, hold_slot, and commit_hold. The agent can reserve a proposed time before a person confirms it, then commit or release that hold. Other tools create calendars, replace weekly availability, list bookings, and cancel them.
The same operation can cover several calendars, such as equipment and staff. A commit succeeds for all requested calendars or for none. Responses use typed errors including CONFLICT, EXPIRED, INVALID, and NOT_FOUND; timestamps must be RFC 3339 values with an explicit offset.
You need a deltat server version 0.4.0 or later and DELTAT_PASSWORD. Without DELTAT_PASSWORD, the MCP server refuses to start. The package runs through npx, with host, port, database, and user supplied through environment variables.
What it helps with
- find an open time across selected calendars
- hold a slot while a person decides
- commit linked bookings as one operation
- release a time that is no longer needed
- list or cancel an existing booking
Example prompts for the agent
- Create a calendar called “Haircuts”, set weekday afternoon availability, and find the first open 30-minute slot tomorrow.
- Find a time when the equipment and crew calendars are both free, hold it, then commit it after I confirm.
- If the requested time conflicts, show alternatives and hold the one I choose with
hold_slot.
How to install deltat
Platform CLI
claude mcp add --env DELTAT_PASSWORD=<DELTAT_PASSWORD> --env DELTAT_HOST=<DELTAT_HOST> --env DELTAT_PORT=<DELTAT_PORT> --env DELTAT_DATABASE=<DELTAT_DATABASE> --env DELTAT_USER=<DELTAT_USER> --transport stdio mcp -- npx -y @open-deltat/mcpReplace <…> with your own values. 2 more environment variables are in the server README
Platform CLI
codex mcp add mcp --env DELTAT_PASSWORD=<DELTAT_PASSWORD> --env DELTAT_HOST=<DELTAT_HOST> --env DELTAT_PORT=<DELTAT_PORT> --env DELTAT_DATABASE=<DELTAT_DATABASE> --env DELTAT_USER=<DELTAT_USER> -- npx -y @open-deltat/mcpReplace <…> with your own values. 2 more environment variables are in the server README
Config file
{
"mcpServers": {
"mcp": {
"command": "npx",
"args": [
"-y",
"@open-deltat/mcp"
],
"env": {
"DELTAT_PASSWORD": "<DELTAT_PASSWORD>",
"DELTAT_HOST": "<DELTAT_HOST>",
"DELTAT_PORT": "<DELTAT_PORT>",
"DELTAT_DATABASE": "<DELTAT_DATABASE>",
"DELTAT_USER": "<DELTAT_USER>"
}
}
}
}Replace <…> with your own values. 2 more environment variables are in the server README
Config file
{
"servers": {
"mcp": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@open-deltat/mcp"
],
"env": {
"DELTAT_PASSWORD": "<DELTAT_PASSWORD>",
"DELTAT_HOST": "<DELTAT_HOST>",
"DELTAT_PORT": "<DELTAT_PORT>",
"DELTAT_DATABASE": "<DELTAT_DATABASE>",
"DELTAT_USER": "<DELTAT_USER>"
}
}
}
}Replace <…> with your own values. 2 more environment variables are in the server README
Platform CLI
gemini mcp add -e DELTAT_PASSWORD=<DELTAT_PASSWORD> -e DELTAT_HOST=<DELTAT_HOST> -e DELTAT_PORT=<DELTAT_PORT> -e DELTAT_DATABASE=<DELTAT_DATABASE> -e DELTAT_USER=<DELTAT_USER> mcp npx -y @open-deltat/mcpReplace <…> with your own values. 2 more environment variables are in the server README
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about deltat
How do I install deltat in Claude Code?
Run claude mcp add deltat -e DELTAT_PASSWORD=<DELTAT_PASSWORD> -- npx -y @open-deltat/mcp in your terminal.
What does deltat do?
It gives an agent calendar tools for finding availability, holding a slot, and committing a booking atomically. It also supports multiple calendars, availability settings, and cancellations.
What does deltat require?
Use a deltat server version 0.4.0 or later and set DELTAT_PASSWORD. Timestamps must use RFC 3339 with a required timezone offset.
