# Seneschal Block Value API

> Seneschal Block Value API is a paid API for AI agents from api.seneschal.space, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Returns a statistical snapshot of Ethereum block value (MEV + fees) over a recent time window at a given percentile.

## Facts

- Endpoint: GET https://api.seneschal.space/v1/q/block-value
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/seneschal-block-value-api-ce9e7fc9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_21AfRxeMtlhy0A_lazrBw

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-block-value-api-ce9e7fc9
```

Example prompt: What's the 90th percentile Ethereum block value over the last 7 days — I want to know how much ETH top block proposers are capturing?

## When to prefer this

Choose this endpoint when you need a quick statistical summary of Ethereum block proposer revenue (MEV + fees) without setting up an Ethereum node or connecting to a heavy indexer. It is especially useful for agents doing validator economics analysis, MEV benchmarking, or fee market research that need a single data point priced at fractions of a cent, with no API key or account required.

## Known failure modes

- Invalid percentile value outside 1-99 range returns an error
- Unrecognized window string (not 24h, 7d, or 30d) returns an error
- Insufficient payment or missing x402 payment header returns HTTP 402
- Temporary data unavailability may return a 503 or stale timestamp

## How this service works

Single-fact: network-wide percentile block value (proposer payment, ETH) across ALL winning slots in the window — the "is it worth bundling?" number, independent of builder. Returns {value_eth, median_eth, max_eth, samples}.

## Output

A JSON object containing the requested percentile block value in ETH, the median block value in ETH, the maximum block value in ETH, the number of samples analyzed, total slots counted, the lookback window used, and the timestamp of the data snapshot.

## 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",
     "properties": {
      "pct": {
       "type": "string",
       "description": "Percentile 1-99 (default 50)."
      },
      "window": {
       "type": "string",
       "description": "Lookback window: 24h, 7d or 30d (default 24h)."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "pct": {
       "type": "integer"
      },
      "window": {
       "type": "string"
      },
      "max_eth": {
       "type": "number"
      },
      "samples": {
       "type": "integer"
      },
      "as_of_ms": {
       "type": "integer"
      },
      "value_eth": {
       "type": "number"
      },
      "median_eth": {
       "type": "number"
      },
      "total_slots": {
       "type": "integer"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "pct": 50,
  "window": "24h",
  "max_eth": 1.92,
  "samples": 7180,
  "as_of_ms": 1765532000000,
  "value_eth": 0.031,
  "median_eth": 0.031,
  "total_slots": 7180
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/seneschal-block-value-api-ce9e7fc9/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)