AI Agents or Partners

POSThttps://saveproptax.com/api/agent/check · keyless · optional x-agent-key header

curl -s https://saveproptax.com/api/agent/check \
  -H 'Content-Type: application/json' \
  -d '{"address": "123 Main St, Walnut Creek"}'

Add "unit": "Unit 12" for multi-unit buildings. A qualifying response:

{
  "status": "qualifies",
  "message": "This property qualifies: recent comparable sales support a value of
    $915,000 against the $1,024,000 assessment, an estimated $1,204 per year in
    tax savings; filing costs a flat $29 and the owner signs and pays.",
  "property": { "address": "123 MAIN ST, WALNUT CREEK CA", "county": "Contra Costa" },
  "estimate": { "assessment": 1024000, "opinion": 915000, "estimatedAnnualSavings": 1204 },
  "filing": { "feeUsd": 29, "deadline": "November 30, 2026" },
  "continueToken": "eyJ...signed, valid 24 hours",
  "cached": false,
  "checkedAt": "2026-08-19T18:00:00.000Z"
}

estimate appears when a valuation was computed (qualifies and fair_assessment). filing appears when filing terms are relevant (qualifies and window_closed). continueToken appears only on qualifies. message is always a one-sentence explanation you can relay to your user as is.

Every status your integration must handle

POSThttps://saveproptax.com/api/agent/prepare

curl -s https://saveproptax.com/api/agent/prepare \
  -H 'Content-Type: application/json' \
  -d '{
    "continueToken": "eyJ...from a qualifying check",
    "ownerName": "Jane Homeowner",
    "ownerPhone": "925 555 0100",
    "ownerEmail": "jane@example.com"
  }'

{
  "docId": "d0c1d2...",
  "status": "awaiting_signature",
  "statusUrl": "https://saveproptax.com/api/agent/status?doc=d0c1d2...",
  "ownerEmailSent": true
}

We fill the county's own review form, attach the comparables worksheet, create the e-sign document, and email the signing link to ownerEmail. The response never contains the signing link. The owner name goes on the county form exactly as sent, so it should match title. Phone numbers need an area code. Limited to 3 prepares per owner email per day; the token must come from a check less than 24 hours old, and the window and one-filing-per-year guard are re-checked at prepare time.

Errors return { "error": "relayable message" } with 400 (bad input), 401 (bad or expired token), 409 (already filed, or the evidence refreshed and the numbers changed: run a fresh check), 422 (window closed), or 429 (owner email at its daily link limit).

GEThttps://saveproptax.com/api/agent/status?doc=<docId>

curl -s 'https://saveproptax.com/api/agent/status?doc=d0c1d2...'

{ "status": "filed", "updatedAt": "2026-08-19T18:30:00.000Z",
  "message": "Payment is complete and the filing is on its way to the County Assessor." }

Coarse states only: awaiting_signature → awaiting_payment → filed → delivered. No personal information, no addresses, no amounts, ever. Unknown or invalid ids return { "status": "unknown" }.

POSThttps://saveproptax.com/api/agent/register · instant, no approval step

curl -s https://saveproptax.com/api/agent/register \
  -H 'Content-Type: application/json' \
  -d '{"agentName": "MyAssistant", "contactEmail": "dev@example.com"}'

Returns a key immediately. Send it as the x-agent-key header on check and prepare calls. A key buys double the fresh-check headroom under the hourly budget and named attribution in our funnel (useful once you want to talk partnership: your traffic has a name). Anonymous use works fine for trying it out; registration is identity, not permission.

A remote MCP server over streamable HTTP, no auth, stateless:

https://saveproptax.com/mcp

• Claude: Settings → Connectors → Add custom connector → paste the URL.
• ChatGPT: Settings → Connectors (or Apps) → add an MCP server by URL, where your plan supports custom connectors.
• Any MCP client: point a streamable-HTTP transport at the URL; no token needed.

Tools, mirroring the endpoints above:

Same rules as the HTTP API: start_filing emails the owner and never returns the signing link in the tool result.

• Per-address cache, 24 hours. Repeat checks of the same address are instant, free to us, and marked cached: true. Cached answers are never rate limited.
• Hourly fresh-check budget. Fresh checks spend real money on records and sales data, so they share an hourly pool (registered keys get double headroom). Under heavy load fresh checks answer busy while cached answers still serve; the pipeline never degrades to a cheaper method, it only delays. The number an agent sees is the number the website shows is the number that gets filed.
• Per-IP backstop. Generous, and deliberately secondary: major assistants egress from shared IP pools.
• Prepare gating. Prepare requires a valid token from a real check and is limited to 3 signing links per owner inbox per day.

• 18 pilot counties: Alameda, Contra Costa, Los Angeles, Marin, Napa, Placer, Riverside, Sacramento, San Benito, San Bernardino, San Francisco, San Joaquin, San Mateo, Santa Clara, Santa Cruz, Solano, Sutter, Yolo. Windows are seasonal per county; see current windows and deadlines.
• Qualifying floor: we only say qualifies when estimated savings exceed $500 a year; below that, a filing is not worth the owner's effort and we say so.
• Flat $29, paid by the owner after signing. No percentage of savings, no subscription.
• The check is free either way: the comparable sales we find are the owner's to use, including filing directly with their county at no charge.