# Seneschal Builder Bid Query

> Seneschal Builder Bid Query is a paid API for AI agents from api.seneschal.space, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Retrieves the current Ethereum mainnet block builder bid from Seneschal's MEV-boost compatible block builder

## Facts

- Endpoint: GET https://api.seneschal.space/v1/q/builder-bid
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/seneschal-builder-bid-query-53979979
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_psIXWKkJRRMigDEVLAFj2

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 seneschal-builder-bid-query-53979979
```

Example prompt: What is the current block builder bid from Seneschal's Ethereum mainnet block builder right now?

## When to prefer this

Use this endpoint when you need to query a live Ethereum mainnet block builder bid, particularly in MEV-boost validator setups or when monitoring block building activity. Prefer Seneschal's builder if you also use their private payment watch service and want a unified payment model via x402 USDC on Base.

## Known failure modes

- No current bid available if no block is being actively built
- Payment required (402) if USDC x402 balance is insufficient
- Invalid or malformed query parameters return 400 error
- Builder temporarily offline or between slots returns empty response
- Rate limiting if too many requests in short succession

## How this service works

Single-fact: percentile bid value (in ETH) for `builder` over the window. Returns {value_eth, samples}.

## Output

Returns the current builder bid from Seneschal's Ethereum mainnet block builder, including the bid value, block payload metadata, and related MEV data useful for validators or block proposers evaluating builder bids.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "builder"
     ],
     "properties": {
      "pct": {
       "type": "string",
       "description": "Percentile 0-100 (default 50)."
      },
      "window": {
       "type": "string",
       "description": "Lookback window: 24h, 7d or 30d (default 24h)."
      },
      "builder": {
       "type": "string",
       "description": "Builder name (substring match)."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "samples": {
       "type": "integer"
      },
      "value_eth": {
       "type": "number"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "samples": 412,
  "value_eth": 0.22
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/seneschal-builder-bid-query-53979979/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.seneschal.space](https://www.zero.xyz/host/api.seneschal.space/llms.txt)