Altos MCP Server

Altos Research — Real-Time Real Estate Market Data

Altos Research is the industry's standard for weekly-cadence US real estate market statistics: median list prices, price reductions, days on market, inventory by ZIP / metro / state, broken out by property type (single-family, condo) and market quartile. Where MLS data is fragmented and lagged, Altos aggregates and publishes weekly.

Part of Pipeworx — an MCP gateway connecting AI agents to 1861+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Why this matters for AI agents

Most public housing data (Census ACS, FRED home price index) updates monthly or quarterly. Altos updates weekly with the data agents and lenders actually use to gauge market temperature. If an agent is answering "is this market hot or cold right now?" the Altos data is most fit-for-purpose.

Common flows:

• Metro stats. altos_market_stats({region: "us-co-denver"}) → median list, days on market, inventory, weekly trend.
• Property type filter. Same call with res_type: "single_family" or "condo".
• Quartile filter. quartile: "FIRST" to focus on the bottom-quartile market (entry-level), "FOURTH" for luxury.
• Multi-metro comparison. Iterate calls in parallel for a peer comparison.

Used by the housing_property_report and housing_market_brief compounds.

Auth

Altos is a paid commercial data product. Two paths:

1. BYO key: get an Altos partner key directly (commercial relationship), pass via _altosKey.
2. Pipeworx Housing Vertical: subscribe at pipeworx.io/account and Pipeworx fronts the relationship. No _altosKey needed.

The vertical option is the common case — most agents using Altos also want ATTOM, FRED, and BLS for housing analysis. Bundling them is cheaper than separate keys.

Region codes

Altos uses geo-coded region IDs:

Smaller geographies have noisier data — single-ZIP weekly stats can swing wildly with low listing counts.

Update cadence

Weekly, typically published Monday or Tuesday for the prior week's data. Pipeworx caches with 24-hour TTL; intra-week, the same number is returned (Altos doesn't intra-week update).

Common pitfalls

• List vs. sale price. Altos primarily tracks active listings — list price, days on market, price reductions. Sale prices and YoY-sale-price-change come from county records (ATTOM) and have longer lag. Don't conflate "Altos median price" with "sold for."
• Active inventory ≠ months-of-supply. Altos gives you the level; months-of-supply (a more interpretable metric) needs absorption rate too. Compute as inventory / monthly sales rate.
• Quartile semantics. Altos splits the market into 4 price quartiles per region. The first quartile is bottom 25%, fourth is top 25%. Quartile boundaries are recomputed each week.
• Property type changes coverage. Single-family is universally covered; condos exist in metros where condos are common (urban centers). Rural metros may return null for condo queries.
• "This week" gets revised. The most recent week is provisional and gets revised slightly the following week as more listings flow in. Don't deploy production decisions on the most-recent-week number alone.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "altos": {
      "url": "https://gateway.pipeworx.io/altos/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/altos/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1861+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/altos_market_stats \
  -H 'Content-Type: application/json' \
  -d '{"_altosKey":"your-altos-api-key","region":"us_national"}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/altos_market_stats. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Run it from npm

@pipeworx/mcp-altos is a local stdio bridge to the Pipeworx gateway: your MCP client starts it with npx, and it forwards every call to the same https://gateway.pipeworx.io/altos/mcp endpoint shown above. It needs network access; there is no offline mode.

{
  "mcpServers": {
    "altos": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-altos"]
    }
  }
}

Without a key it calls anonymously, capped at 50 calls a day. A free account raises that to 200 a day: get a key at https://pipeworx.io/signup and add "env": { "PIPEWORX_API_KEY": "<your key>" } to the server entry. The key is sent as a Bearer token, the same way a hosted connection sends it, so calls are metered and billed exactly as they are there.

It lists only this pack's tools by default. Set PIPEWORX_META_TOOLS=1 to also list ask_pipeworx and the other gateway-wide tools.

Behind an HTTPS proxy: Node's built-in fetch does not read HTTPS_PROXY by default. Newer Node releases honour it when NODE_USE_ENV_PROXY=1 is set; check your Node version's documentation.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Altos data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides
• pipeworx.io

License

MIT