Claude Code Date Math stay_calculator
How to: Claude Code Date Math stay_calculator
Add Date Math to Claude Code
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01
Run this in your project directory.
claude mcp add --transport http date-math https://date-math.datemath.workers.dev/mcp-
02
Restart your session so the server is picked up.
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03
Ask for something stay_calculator does. Claude Code lists the server's tools on connect and calls stay_calculator itself — you do not invoke it by name.
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04
If nothing happens, check the server is running and that Date Math's identifier in your config matches the one above exactly.
Adds it for this project only. Append --scope user to make it available everywhere. Claude Code docs
Set these first
Date Math will not start until these are set, so stay_calculator never becomes available.
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DATE_MATH_PRIVATE_KEY -
DATE_MATH_MAX_PRICE
Same tool, other clients
This list was read from the server itself, by connecting to it and calling tools/list on 14 November 2026. It is what
the server actually exposes, not what its listing claims.
Mutating and Read-only are read off each tool's name, not its schema — a hint, not a guarantee. The registry stores tool names only; connect the server for its live schemas.