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Washington closing math, sourced county facts, permit history, environmental mapping and local housing context. Bring them into the software you build and the AI assistant you already use.
REST + MCP · 4 counties of property records
The workflow
“What changes if my seller accepts a lower price with fewer concessions?”
Use an address, an asking price and the seller's actual costs.
Compare scenarios and offers using the same deterministic math.
Return proceeds, source dates, assumptions and gaps together.
Calculations run in code. Records carry source context. The seller packet returns JSON and report text for your application to present.
Call REST endpoints and consume structured JSON.
MCP gives a compatible client named tools to call.
Both interfaces use the same service and calculation engines.
Run a real REET estimate here, or paste the request into your terminal. Public REET, net-sheet and deadline calculators need no signup.
curl -s https://app.sentineliq.net/api/v1/public/reet \
-H 'Content-Type: application/json' \
-d '{"sale_price":750000,"county":"king"}'For $750,000 in King County, the current calculator returns $8,655 state REET, $3,750 local REET and a $5 technology fee: $12,410 estimated total. This is a worked example, not a quote for a specific closing.
Local tax uses a county-level assumption. Exact location codes and transaction type can change the result. Preserve the assumptions and disclaimers returned with each answer.
Create a key in the console, save it as SENTINEL_API_KEY on your server, and check your identity and allowance. This probe is free.
curl -s https://app.sentineliq.net/api/v1/agent-api/v1/whoami \ -H "Authorization: Bearer $SENTINEL_API_KEY"
The key is shown once. Keep it out of browser code and source control. Up to five active keys share one account allowance; you can revoke any key in the console.
Start with the public calculators. These examples use an HTTP MCP connection; your client must support remote MCP. Client availability and configuration vary.
{
"mcpServers": {
"sentinel": {
"url": "https://app.sentineliq.net/api/v1/mcp/public"
}
}
}{
"servers": {
"sentinel": {
"type": "http",
"url": "https://app.sentineliq.net/api/v1/mcp/public"
}
}
}claude mcp add --transport http sentinel https://app.sentineliq.net/api/v1/mcp/public
For the full tool set, use /api/v1/mcp and configure Authorization: Bearer agk_… through your client's protected credential settings. Header authentication is required; there is no OAuth sign-in flow. Do not put a real key in a shared configuration file.
A seller packet combines seller scenarios with optional property, permit and market evidence. It returns a readable report alongside structured results, source dates, assumptions and any data gaps.
Start with these three prices, seller credits and a known mortgage payoff. This example works without a property or market lookup. Add an address and market area when your workflow needs sourced context.
Omitted payoff or seller credits mean unknown; enter zero only when none apply. Results label the proceeds basis and leave scenario differences blank when the supplied costs cannot be compared.
The packet is a research and calculation aid, not an appraisal or a comparative market analysis. It does not fetch comparable sales.
Explore request and response schemas →Generated example · King County
Caller-supplied scenarios, $420,000 payoff and a 5% commission assumption. Proceeds include the credits shown.
| Sale price | Credits | Est. proceeds |
|---|---|---|
| $725,000 | $0 | $254,285 |
| $750,000 | $5,000 | $272,540 |
| $775,000 | $10,000 | $290,795 |
Buyer payment example: $4,492.41/mo
$750,000 price, 20% down, supplied 6.5% rate, 30-year term. Includes estimated tax and insurance. This is not a lender quote. Property and market lookups were not requested.
Not legal, tax, or financial advice. Verify with licensed professionals and source records.
{
"county": "king",
"scenarios": [
{
"label": "Conservative",
"sale_price": 725000,
"mortgage_balance": 420000,
"concessions": 0
},
{
"label": "Target",
"sale_price": 750000,
"mortgage_balance": 420000,
"concessions": 5000
},
{
"label": "Stretch",
"sale_price": 775000,
"mortgage_balance": 420000,
"concessions": 10000
}
],
"monthly_payment": {
"sale_price": 750000,
"interest_rate_pct": 6.5,
"down_payment_pct": 20
}
}Keyed REST paths start at /api/v1/agent-api/v1/. The three public calculators use /api/v1/public/. MCP names map to the same operations.
| REST route | MCP tool | What comes back | Access |
|---|---|---|---|
| POST /reet | wa_reet | Graduated state REET, county local estimate and fee. | Public + key |
| POST /net-sheet | wa_net_sheet | Itemized seller costs and estimated proceeds. | Public + key |
| POST /deadlines | nwmls_deadlines | Default deadlines, business-day rules and assumptions. | Public + key |
| GET /property | wa_property_lookup | Address or parcel lookup with field sources, dates and gaps. | Key |
| GET /permit-history | wa_permit_history | Seattle, Everett and Pierce County permits, dates and observed changes. | Key |
| GET /site-context | wa_site_context | FEMA and WGS mapping with explicit coverage and observation dates. | Key |
| GET /local-context | wa_local_context | Census housing, scheduled Metro stops and OSPI language programs. | Key |
| GET /market | wa_market_snapshot | Dated area snapshot and freshness status. | Key |
| POST /seller-scenarios | wa_compare_seller_scenarios | Seller outcomes across prices and concessions. | Key |
| POST /offers/compare | wa_compare_offers | Supplied offers and their estimated seller proceeds. | Key |
| POST /monthly-payment | wa_monthly_payment | Payment estimate using your loan assumptions. | Key |
| POST /seller-packet | wa_seller_packet | Seller math, optional property, permit and market evidence, and a report. | Key |
Property records cover King, Pierce, Snohomish and Whatcom. Look up an address or a county and parcel number. Each field distinguishes observed, unverified, missing and withheld data. Source observation dates stay separate from publication dates; legacy fields are not silently certified. REET local-rate assumptions cover eleven counties, separately from property coverage.
Status, price and days on market appear only for a matched licensed listing already on file. Null means no licensed listing on file, not that a property is off market. Listing links, photos and portal AVMs are absent.
Inspect application, issue and completion dates, status, units added or removed, reported project cost and source links. Add include_permits: true to a seller packet with a property lookup. Subsequent source observations track changes as Sentinel sees them.
This feed covers the City of Seattle. Records are associated by street, unit and ZIP; the source does not supply parcel IDs. A building permit is not proof of work on a particular unit. No match does not mean no permits, and a permit's zoning label does not establish current development rights.
REST errors include a machine-readable detail.code and message. Keep X-Request-Id for support. A 401 means the key needs attention, 402 means the account needs a plan, 404 means no matching record, 422 means inputs need correction, and 429 means a limit was reached. Honor Retry-After.
Successful answers consume the account allowance. Validation failures, misses, rejected requests and identity probes do not. MCP discovery is also free. The console shows the allowance that actually applies to your account.
$250
One payment · 30 days · no automatic renewal
We will confirm the workflow, access and payment directly before the pilot starts.
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to start
The pilot is one developer account with up to five integration keys, not five user seats. Checkout is offered when payment setup is available; otherwise request setup directly. Existing paid accounts retain their API access. The 30-day pilot is a one-time payment and does not renew automatically.
An address, a seller question and the place you want the answer to appear.