Hex-binned density for maps
h3_densityHex-binned stock and transaction density for map layers, at H3 resolution 8.
Same call over REST
H3 density/v1/h3/density/{area_id}Not connected yet? Connect your assistant. Sign in with your MarketCode account; no API key needed.
Reference
What h3_density answers
DENSITY ONLY. There is no usable price per cell — the hex cube's price column is populated on about 2% of rows and its rental, EPC and per-m2 columns are empty. The response lists what is and is not available; do not offer a price heatmap from this.
tx_n is the transaction COUNT and tx_value is the total in pounds.
UK only.
Inputs
Before you call it
- area_id
- The area id is the analytics area identifier, not a name or a GSS code. Call area_resolve with a place name or code ("Hackney", "E5") first; it is free and returns the id with the area's hierarchy. Where it gives both
area_idandanalytics_area_id, passanalytics_area_id.
Example
An example call to h3_density
Use the MarketCode tool h3_density with {"area_id":"c0694b59-04d1-48ab-9a4c-c4f9d7b74f60","limit":3} and show me the result.{
"area_id": "c0694b59-04d1-48ab-9a4c-c4f9d7b74f60",
"resolution": null,
"cells": [],
"count": 0,
"available": [
"stock_count",
"tx_n",
"tx_value"
],
"not_available": "price per cell — h3_facts.tx_price_median is populated on ~2% of rows and the psm, rental, EPC and AVM columns are empty",
"credits_charged": 0
}A real response, captured from production and trimmed: arrays to three items, long strings shortened, volatile keys dropped.
Inputs
Arguments h3_density takes
| Name | Type | Required | Description |
|---|---|---|---|
| area_id | string | Yes | |
| limit | integer | No | Default: 2000 |
Response
What comes back
| Field | Type | Example |
|---|---|---|
| area_id | string | c0694b59-04d1-48ab-9a4c-c4f9d7b74f60 |
| resolution | null | |
| cells | array | |
| count | integer | 0 |
| available | array | |
| not_available | string | price per cell — h3_facts.tx_price_median is pop |
| credits_charged | integer | 0 |
Fields observed in the example response above; a field the example did not exercise is not listed.
Usage
How to run h3_density in your assistant
Ask your assistant in plain English, for example:
"Use the MarketCode tool h3_density for <address or area>.
Show the result and the credits charged."
The arguments the assistant will send, for the example on this page:
{"area_id":"c0694b59-04d1-48ab-9a4c-c4f9d7b74f60","limit":3}The connect steps for Claude, ChatGPT, Codex, Cursor and Claude Code are on the MCP page.
Price and licence
What it costs, and where the data comes from
h3_density is free over MCP and over REST, and the two surfaces share one credit balance. Free calls need a signed-in account or an API key and appear in your usage, but they never touch your balance.
Credits are granted on sign-up and bought in packs; the pricing page lists every call.
Sources
- HM Land Registry
Price Paid Data
Open Government Licence v3 · England and Wales
- Ordnance Survey
National Geographic Database (buildings, land and sites)
Used under licence from Ordnance Survey · Great Britain
Related
Tools used with h3_density
- Built-stock profile of an areaFree
area_stock_profileComposition of the built stock in an area: unit counts, HMO share, mixed-use share, median building height and footprint, solar penetration.Same category - Physical form of buildings3 credits
building_physicalPhysical form of the buildings a set of UPRNs sit in: height, volume, footprint area, floor count, construction and roof material, basement, green roof, solar panels, and the residential/commercial unit mix.Same category - Mixed-use buildings in an area6 credits
mixed_use_buildingsBuildings holding BOTH residential and commercial units — the conversion and permitted-development cohort.Same category - Plot utilisation of land parcels6 credits
plot_utilisationLand parcels by size and how much of them is built on. Set `max_built_coverage` to 0.2 to find largely undeveloped plots.Same category
FAQ
Questions about h3_density
How much does `h3_density` cost?
+
h3_density is free over MCP and over REST, and the two surfaces share one credit balance. Free calls need a signed-in account or an API key and appear in your usage, but they never touch your balance.
Where do I get the area id?
+
From area_resolve, which is free: give it a place name or postcode district and it returns the area id, centroid and hierarchy. h3_density then takes that id.
Which assistants can run `h3_density`?
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Any MCP client: Claude (claude.ai, Claude Desktop, Claude Code), ChatGPT in developer mode, Codex and Cursor, each documented on the MCP page. You sign in with your MarketCode account over OAuth; there is no key to paste, and the connection is read-only.
Where does the data come from?
+
Read from HM Land Registry price paid data and Ordnance Survey NGD. Coverage is the UK.
Does `h3_density` change anything?
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No. The tool is annotated read-only on the server, so it never writes to your data or ours and an assistant can call it without a confirmation step.
Try h3_density in your assistant.
30-minute call. We'll connect your assistant live on a real address.