SavePropTax MCP server

A remote MCP server and an open HTTP API for California property tax appeals.

Ask it whether a home is over-assessed. If recent comparable sales support a lower value, it prepares the county's own Proposition 8 decline-in-value review form and emails a signing link to the homeowner. The owner signs and pays a flat $29. Checking is free, keyless, and can only ever lower a tax bill, never raise it.

There is nothing to install. The server is hosted:

https://saveproptax.com/mcp

Streamable HTTP, no authentication, stateless.

Add it to a client

Claude: Settings, then Connectors, then Add custom connector, and paste the URL above.

ChatGPT: Settings, then Connectors (or Apps), then add an MCP server by URL, where your plan supports custom connectors.

Claude Code:

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

Any MCP client: point a streamable-HTTP transport at the URL. No token.

Tools

Tool	Arguments	What it does
check_property_tax_savings	address (required), unit	Free check of one California home. Returns a status, the current assessment, an opinion of value from recent comparable sales, and estimated annual savings. A qualifying result carries a continueToken.
start_filing	continueToken, ownerName, ownerPhone, ownerEmail	Prepares the county form and emails the signing link to the owner. The link is never returned to the client.
get_filing_status	docId	Coarse status only: awaiting_signature, awaiting_payment, filed, delivered, unknown. No personal information.

The rule that shapes everything

An agent never handles the signature or the money. The signing link goes to the owner's inbox. The owner reviews the county's own form, signs it, and pays. The worst an anonymous caller can do is spend a free check and send a real homeowner a legitimate link to their own property.

HTTP API

The same capability without MCP. Keyless.

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

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...valid 24 hours",
  "cached": false,
  "checkedAt": "2026-08-19T18:00:00.000Z"
}

Then hand the token and the owner's details to prepare:

curl -s https://saveproptax.com/api/agent/prepare \
  -H 'Content-Type: application/json' \
  -d '{
    "continueToken": "eyJ...",
    "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 }

Poll the status endpoint for progress:

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

Every status to handle

status	meaning
qualifies	Comparable sales support a defensibly lower value, savings exceed $500 a year, and the county window is open. The only status carrying a continueToken.
fair_assessment	Sales do not support a value below the current assessment this year.
not_enough_data	Too few closely matched recent sales for a defensible filing.
not_residential	The parcel's county record is not residential.
window_closed	The county's review window has closed; filing.reopens says when it returns.
county_not_served	A California county not covered yet.
already_filed	A review request was already filed for this property this year.
address_not_found	Retry with the city included.
needs_more_info	The message says what is missing, for example a unit number.
busy	Heavy load: fresh checks briefly paused, cached answers still serve. Retry shortly.

Every message is a relayable one-sentence explanation you can pass to your user as written.

Optional key

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

Returns a key immediately, no approval step. Send it as the x-agent-key header for double the fresh-check headroom and named attribution. Anonymous use works fine; registration is identity, not permission.

Rate limits

• Per-address cache, 24 hours. Repeat checks are instant, cost us nothing, and come back marked cached: true. Cached answers are never rate limited.
• Hourly fresh-check budget. Fresh checks buy real records and sales data, so they share an hourly pool. Under load, fresh checks answer busy while cached answers still serve. The pipeline never degrades to a cheaper valuation method; it only delays.
• Prepare gating. Requires a token from a real check, and is limited to three signing links per owner inbox per day.

Coverage

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, and Yolo counties. Windows are seasonal per county; current deadlines are at https://saveproptax.com/counties.html.

More

• Full reference: https://saveproptax.com/agents
• OpenAPI: https://saveproptax.com/openapi.json
• llms.txt: https://saveproptax.com/llms.txt
• Registry metadata: server.json
• Partnerships and volume arrangements: support@saveproptax.com

SavePropTax prepares review requests from public records and the county's own forms; owners review and sign them. We are not a law firm, and nothing here is legal or tax advice. Reductions are decided solely by the County Assessor.

License

MIT. See LICENSE. The license covers this repository's contents; the hosted service is governed by the terms at https://saveproptax.com/legal.html.

Run locally (stdio)

The hosted server needs no install. For stdio-only MCP clients, this repo ships a dependency-free bridge (Node 18+):

{
  "mcpServers": {
    "saveproptax": {
      "command": "node",
      "args": ["bridge.js"]
    }
  }
}

Or with Docker: docker build -t saveproptax-mcp . && docker run -i saveproptax-mcp. Introspection is answered locally; tool calls are forwarded to saveproptax.com/mcp.