For AI agents — MCP server and JSON API for car leases

Connect

MCP over streamable HTTP, no auth for read and math tools:

{
  "mcpServers": {
    "lease": { "type": "streamable-http", "url": "https://lease.brelsfordsoftware.com/mcp" }
  }
}

Discovery: https://lease.brelsfordsoftware.com/llms.txt · https://lease.brelsfordsoftware.com/.well-known/mcp.json · https://lease.brelsfordsoftware.com/openapi.json. JSON index at https://lease.brelsfordsoftware.com/api/v1.

Tools

calculate_leaseFull payment breakdown with the correct state tax regime. Refuses unverified states.

evaluate_lease_offerGrade a quote; findings with dollar impacts; fills reference rates from site data when the vehicle is named.

compare_lease_vs_buyLease vs loan over the lease term, equity-adjusted.

get_lease_tax_treatmentRegime, rate, citation and worked example for a state; or the verified list.

optimize_security_depositsEvery deposit count priced for lenders that accept MSDs.

list_lease_offersLive advertised offers ranked by true cost; state filter adds a tax estimate.

get_lease_offerOne offer, optionally with a state estimate.

get_market_ratesObserved money factors and residuals from signed deals and derived rates. Never a buy rate.

list_signed_dealsPublished, anonymised signed leases.

submit_signed_dealContribute a signed contract's figures (with the user's consent).

submit_advertised_offerSubmit an offer seen on an OEM or dealer page.

create_lease_requestPost a request brokers can answer; returns a private status link.

get_lease_requestRead responses to a request.

register_broker · list_open_lease_requests · respond_to_lease_requestThe broker side, for agents running a desk.

Two prompts front-load the rules that cost most to learn by trial: find-a-lease walks a person from wanting a car to a ranked shortlist and a broker request; check-a-quote turns a dealer worksheet into a verdict and a negotiating list.

Same thing over JSON

curl -X POST https://lease.brelsfordsoftware.com/api/v1/evaluate -H "Content-Type: application/json" -d '{
  "vehicle": {"make": "BMW", "model": "X3"},
  "lease": {"msrp": 52000, "sellingPrice": 47500, "termMonths": 36, "residualPct": 0.59,
            "moneyFactor": 0.00215, "acquisitionFee": 925, "state": "NJ"}
}'

Rules that save you a wrong answer

Money factor is not an APR: APR ÷ 2400 = money factor. 0.00185 is 4.44%. Tools reject values above 0.05 because that is almost always an APR passed by mistake.
Rank by pct_of_msrp: True monthly cost divided by MSRP. At or under 1% is good; under 0.8% excellent. The advertised payment can be set to anything by moving money into the signing amount.
Advertised figures are pre-tax and national: Pass a state to get a per-offer estimate of that state's treatment. Local surtaxes are excluded and the response says which regimes could not be estimated.
Observed rates are not buy rates: Anything from get_market_rates is what people signed for or what an ad implies, with a source. Tell the user that.
Unverified states are refused: Rather than guessed. get_lease_tax_treatment lists the verified ones.
Limits: 120 requests a minute per client. Writes that involve a person (a request, a signed deal) need that person's say-so first.