# Wintergreen Contractor Estimating Q&A

> Wintergreen Contractor Estimating Q&A is a paid API for AI agents from x402.wintergreen.uk, paid per call via x402, $0.005/call, status down (last checked 2026-09-16).

Returns payment-gated answers to contractor estimating questions via a Q&A interface, covering estimation methodology, pricing, and bidding strategies.

## Facts

- Endpoint: GET https://x402.wintergreen.uk/api/v1/knowledge/contractor-estimating/qa
- Price: $0.005/call
- Payment: x402
- Status: down
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/wintergreen-contractor-estimating-q-a-2a95977e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Me295xqXGmGBRqdHNJuG6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability wintergreen-contractor-estimating-q-a-2a95977e
```

Example prompt: Can you pull up the Wintergreen contractor estimating guide and answer this question for me: how should I calculate overhead and profit margin when putting together a bid for a commercial renovation project?

## When to prefer this

Choose this endpoint when an AI agent needs on-demand, authoritative answers about contractor estimating, job costing, bidding strategy, or pricing methodology and is willing to pay $0.02 USDC per query. Prefer this over general web search when you need curated, structured guidance rather than scattered forum advice, and when your agent stack already supports x402 micropayments on Base.

## Known failure modes

- HTTP 402 returned if no valid payment header is included — agent must sign EIP-712 TransferWithAuthorization and retry with X-PAYMENT header
- Empty or irrelevant answer if the question (q parameter) is vague or outside the contractor estimating domain
- Network timeout or service unavailability
- Invalid payment signature or wrong chain (must be Base / eip155:8453)
- Missing required 'q' parameter returns error or empty response

## How this service works

Payment-gated crypto trading intelligence for AI agents.
    
## Categories
- **Hyperliquid Signals**: Real-time funding divergence, lead-lag correlation, liquidation clusters, session volume area levels
- **Quant Methodology**: Backtesting walk-forward validation, strategy generation with kill battery (19 rules), risk management with Kelly sizing, regime detection, execution frameworks, agent orchestration
- **Market Insights**: 22 crypto microstructure observations — funding, liquidation, orderbook, regime, flow, anomaly
- **Power Markets**: ERCOT field guide, merit-order model, duck curve analysis
- **Career Guides**: Firefighter oral board prep, medical coding, ATSA, contractor estimating
- **Trust Scoring**: x402 endpoint verification, P2D badges

## Payment
All paid endpoints return HTTP 402 with USDC on Base (eip155:8453). 
Sign EIP-712 TransferWithAuthorization and retry with X-PAYMENT header.
PayTo: 0xAe9834d71F1Bd989A0dc17593451af823E31CeeD

## Output

A text-based answer to the submitted contractor estimating question, drawn from a curated guide covering bidding methodology, cost calculation, markup, overhead, risk, and job costing — returned after a $0.02 USDC micropayment is authorized via EIP-712 on Base.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "q": {
   "type": "string"
  },
  "_meta": {
   "type": "string"
  },
  "_slug": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/wintergreen-contractor-estimating-q-a-2a95977e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.wintergreen.uk](https://www.zero.xyz/host/x402.wintergreen.uk/llms.txt)