# Base Event Log Monitor

> Base Event Log Monitor is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Monitors and retrieves emitted event logs from a given Base (EVM) address starting from a specified block, with risk scoring and flag assessment.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/base/event-log-monitor
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-event-log-monitor-ad74dffe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iJiul7o7CmDa0qJAO-2Ab

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 base-event-log-monitor-ad74dffe
```

Example prompt: Can you pull all event logs emitted by Base address 0xAbCd1234567890abcdef1234567890abcdef1234 starting from block 12000000 and tell me if there are any risk flags?

## When to prefer this

Use this endpoint when you need to monitor, retrieve, and risk-assess event logs emitted by a specific Base network address from a given block onward. Prefer this over generic RPC calls when you also want automated risk scoring and flag detection bundled with log retrieval, especially in autonomous agent workflows that need to react to on-chain events on Base (EIP-155:8453).

## Known failure modes

- Invalid address format (not matching ^0x[a-fA-F0-9]{40}$) returns a validation error
- Non-numeric or missing from_block returns a schema validation error
- Address with no logs in the specified block range returns empty activity with low risk
- Block number in the future or beyond chain head may return no results or an error
- Payment failure (insufficient USDC or x402 auth issue) results in a 402 response

## How this service works

Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.

## Output

Returns a JSON object with the Base network identifier (eip155:8453), product name, an activity object with event logs, an identity object, an assessment object containing a list of flags, a risk_level (e.g. 'low'), and a numeric risk_score — plus provenance metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address",
      "from_block"
     ],
     "properties": {
      "address": {
       "type": "string",
       "pattern": "^0x[a-fA-F0-9]{40}$",
       "description": "Base address whose emitted logs should be monitored."
      },
      "from_block": {
       "type": "string",
       "pattern": "^[0-9]+$",
       "description": "Return logs from this Base block onward."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "network": {
       "type": "string"
      },
      "product": {
       "type": "string"
      },
      "activity": {
       "type": "object"
      },
      "identity": {
       "type": "object"
      },
      "assessment": {
       "type": "object"
      },
      "provenance": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "network": "eip155:8453",
  "product": "base-event-log-monitor",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-event-log-monitor-ad74dffe/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-agent-preflight.bytoken2023.workers.dev](https://www.zero.xyz/host/base-agent-preflight.bytoken2023.workers.dev/llms.txt)