GardenMaths MCP server

Metric garden maths for Australia and New Zealand inside Claude, ChatGPT, Cursor and VS Code. You can ask:

• how much soil a layered raised bed takes, and whether bags or bulk delivery is cheaper at your prices;

• how much mulch, compost, topsoil or potting mix a job needs;

• what to sow this month in your town;

• how often your town has had a frost after Melbourne Cup Day.

Endpoint: https://mcp.gardenmaths.com/mcp (Streamable HTTP, no sign-in)

Add it in 30 seconds

• claude.ai: Settings → Connectors → Add custom connector → paste the endpoint.

• Claude Code:

  claude mcp add --transport http gardenmaths https://mcp.gardenmaths.com/mcp

• Cursor (.cursor/mcp.json):

  { "mcpServers": { "gardenmaths": { "url": "https://mcp.gardenmaths.com/mcp" } } }

• VS Code (.vscode/mcp.json):

  { "servers": { "gardenmaths": { "type": "http", "url": "https://mcp.gardenmaths.com/mcp" } } }

• ChatGPT: turn on Developer mode (Settings → Security and login), then add a developer-mode app with the endpoint and "No authentication".

Then ask, for example:

My raised bed is 2 m by 1 m and 30 cm deep: 5 cm gravel, 10 cm compost, 15 cm topsoil. Bags are $9, or bulk is $85 a cubic metre plus $70 delivery. What do I need, and which is cheaper?

The answer: 600 L in all, which is 4, 7 and 10 bags of 30 L. Bagged costs $189 and bulk $121, so bulk delivery is cheaper by $68. These are the same figures the GardenMaths site gives and its own tests pin.

Related MCP server: MindOS

Tools

All five tools are read-only and say so in their annotations.

Design

• Ported formulas, pinned to the site. GardenMaths keeps its formulas inside browser scripts that cannot be imported. src/garden.ts ports them line by line, with the site's units, rounding and tie rules, and cites the file and line of each original. The tests pin the raised-bed and potting-mix results the site's own browser tests pin.

• The site's own wording. Each page's allowance label is kept ("for settling and compaction", "for hollows"), along with the method labels, the frost units (BOM nights at 2 °C or below; NIWA ground frosts in New Zealand) and the rule for flagging frost-tender crops.

• No invented prices. Costs use the caller's prices. The site's example prices are offered as illustrative AUD figures, never as quotes or retailer prices.

• Small context cost. The whole tools/list response for the five tools is about 6 KB, roughly 1,600 tokens.

• Forgiving input. It accepts "Hobart TAS", "Mt Gambier", "Whangarei" without the macron, "Lettuces", "kumara" and "silver beet". An input it cannot use is named in the result.

How it's built

• Stack: TypeScript, the official MCP TypeScript SDK v2 and Cloudflare's Agents SDK (createMcpHandler). It runs as a stateless Streamable HTTP server on Cloudflare Workers.

• Protection: Workers Rate Limiting at 60 requests a minute per IP address, and Host/Origin allowlists.

• Data: The planting and frost data are bundled at build time from the GardenMaths repository in a sibling folder. This repository holds the ported formulas, the MCP layer, its tests and the eval. To try the server, use the public endpoint.

Tests and checks

• 27 unit tests (Vitest). They cover:

  • the figures the site's browser tests pin (600 L and 21 bags, $189 vs $121, a 235.6 L round pot, 17.2 L and 72.9 L of potting mix);

  • the frost guide's figures for Cooma, Melbourne and Canberra;

  • regressions for every finding of the review below.

• Independent review before release. Three reviewers checked the server separately:

  • Formula parity with the site's JavaScript. This included 800,000 fuzz cases on bag rounding, with no differences.

  • Claims, attribution and licensing.

  • Live edge cases.

  Their findings were fixed before publishing. Among them were the trailer-payload assumption, NZ ground frosts, frost warnings and name matching.

• Official MCP conformance scenarios: server-initialize, ping and tools-list pass.

• Eval: eval/run.mjs sends 10 realistic questions through Claude Code with only this server connected. It checks that the model called the right tools and quoted the figures they return.

  • Run of 4 Oct 2026, after the review fixes (Claude Sonnet 5.5): 10/10 passed, right tools 10/10. The run before the fixes also scored 10/10.

  • Full table: eval/REPORT.md.

Data and sources

• Formulas and example prices: GardenMaths, a DueRiva project. All results are estimates; confirm quantities with your supplier before you buy.

• Planting calendar: GardenMaths' compilation of the Australian and New Zealand gardening authorities listed on its planting calendar.

• Frost after Cup Day: "GardenMaths analysis of Bureau of Meteorology data via SILO", frost guide, licensed CC BY 4.0; SILO © Queensland Government.

• Monthly frost averages: Bureau of Meteorology in Australia; NIWA (now Earth Sciences New Zealand), mean number of days of ground frost, 1991–2020, in New Zealand.

Need this for your API?

I build tested MCP servers like this one for other companies' APIs: up to 8 tools in 5 business days for a fixed price, with an eval report. See the MCP Server Sprint on Upwork.

Licence

The code in this repository is MIT licensed. The data is not included here and keeps its own terms: the frost analysis is CC BY 4.0 with the credit above, and the planting data is © GardenMaths.