# base-tx-explain

> base-tx-explain is a paid API for AI agents from base-tx-explain.fly.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).

Decodes any Base mainnet transaction into a plain-English JSON summary with action type, assets moved, labeled counterparties, risk flags, and gas cost in USD

## Facts

- Endpoint: POST https://base-tx-explain.fly.dev/mcp
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-tx-explain-65f05419
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HhvXfrtkbasFK79wImSWz

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-tx-explain-65f05419 -d '<json body>'
```

Example prompt: Can you explain what happened in this Base mainnet transaction — I need a plain-English breakdown of what action was taken, which assets moved, who the counterparties are, any risk flags, and the gas cost in dollars?

## When to prefer this

Choose this endpoint when you need a fast, deterministic, structured decode of a Base mainnet transaction — especially when auditability or reproducibility matters and you cannot tolerate LLM-introduced variability. Ideal for compliance workflows, wallet UX enrichment, or agent pipelines that need to act on structured transaction data. Prefer this over general-purpose LLM-based blockchain explainers when consistency and strict JSON output are required.

## Known failure modes

- Invalid or non-existent transaction hash returns an error
- Transaction not found on Base mainnet (e.g. it's on a different chain) returns an error
- Malformed MCP input schema causes a 400-level rejection
- Payment not included or insufficient USDC triggers a 402 response
- Unrecognized contract addresses may result in unlabeled counterparties

## How this service works

Plain-English, deterministic decode of any Base mainnet transaction. Strict JSON: summary, action type, assets moved, labeled counterparties, risk flags, gas in USD. No LLM in the response path.

## Output

A strict JSON object containing: a plain-English summary of the transaction, the action type (e.g. swap, transfer, mint), a list of assets moved with amounts and directions, labeled counterparties (e.g. known contracts or wallets), risk flags (e.g. interaction with flagged contracts), and the gas fee expressed in USD. The decode is deterministic — no LLM is used in the response path.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "toolName",
    "inputSchema"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "mcp"
    },
    "example": {
     "type": "object"
    },
    "toolName": {
     "type": "string"
    },
    "description": {
     "type": "string"
    },
    "inputSchema": {
     "type": "object"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-tx-explain-65f05419/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-tx-explain.fly.dev](https://www.zero.xyz/host/base-tx-explain.fly.dev/llms.txt)