The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Civic Library MCP listing page.
An MCP server that gives AI agents clean, token-efficient access to US civic & property data — geocoding, census tracts, Opportunity Zones, ACS demographics, and FEMA flood zones — sourced entirely from free federal open data.
No scraping, no paid keys for the core tools, no proprietary databases. Just the official sources (U.S. Census Bureau, U.S. Treasury CDFI Fund, FEMA), wrapped in a small set of well-described tools that return compact JSON instead of the bloated payloads most data MCPs dump into your context window.
Built for developers working on proptech, real-estate, fintech, civic tech, GIS, and housing research with AI agents.
| Tool | What it does | API key? |
|---|---|---|
geocode_address | US street address → lat/lng + state, county, and 2020 census tract GEOID | None |
lookup_census_tract | lat/lng → the 2020 census tract (with county/state) containing that point | None |
check_opportunity_zone | Is this address / point / tract in a designated Qualified Opportunity Zone? | None |
get_tract_demographics | ACS 5-Year indicators (income, population, home value, poverty rate, …) for a tract | Free Census key |
check_flood_zone | lat/lng → FEMA flood-hazard zone + whether it's a Special Flood Hazard Area | None |
Four of the five tools work with zero configuration. Only get_tract_demographics needs a free Census API key (see below).
Add to your MCP config (e.g. claude_desktop_config.json):
The CENSUS_API_KEY line is optional — leave it out and four of the five tools still work.
get_tract_demographics calls the U.S. Census ACS Data API, which requires a free key. Get one in ~30 seconds at https://api.census.gov/data/key_signup.html and set it as CENSUS_API_KEY in the server's environment.
Check whether a property is in an Opportunity Zone:
Flood risk for a coordinate:
Tract demographics (needs a key):
Opportunity Zone designations are keyed to 2010 census tract boundaries, but the default Census geocoder returns 2020 tracts — and tract GEOIDs changed between the two vintages. A naive lookup that matches a 2020 GEOID against the OZ list will silently return wrong answers near any boundary that moved.
check_opportunity_zone handles this correctly: it re-resolves the address/coordinate to its 2010 tract before matching. (You can see the difference — the same address can yield GEOID …980000 from geocode_address and …006202 from check_opportunity_zone.) If you pass tract_geoid directly, it's treated as a 2010 GEOID.
| Data | Source | Notes |
|---|---|---|
| Geocoding & census tracts | U.S. Census Bureau Geocoder | Public domain |
| Opportunity Zones | U.S. Treasury CDFI Fund | Round 1 (2018) designations, 8,764 tracts, bundled |
| Demographics | U.S. Census ACS 5-Year | Public domain; free key required |
| Flood zones | FEMA National Flood Hazard Layer | Public domain |
All underlying data is U.S. federal open data (public domain). This software is MIT-licensed.
The bundled Opportunity Zone list is regenerated with npm run build:oz.
This tool surfaces public government data for informational purposes. It is not legal, financial, tax, insurance, or investment advice. Opportunity Zone, flood-zone, and demographic determinations should be confirmed against the official source of record before relying on them for any transaction. Data is provided "as is" with no warranty.
Issues and PRs welcome — especially additional federal open-data sources and ACS fields. Keep responses compact (token cost is a feature) and every data point attributed to its source.
MIT © 2026 Adrian Cisneros