← AgentTrust ← Blog

How to Build an ElizaOS Plugin for On-Chain Reputation

ElizaOS is the leading framework for building autonomous AI agents. By creating a plugin, you can give any ElizaOS agent the ability to check on-chain wallet reputation — enabling trust-aware decision making.

This guide walks through building an ElizaOS plugin that integrates with AgentTrust for on-chain reputation scoring.

Prerequisites

• Node.js 18+ and npm
• An ElizaOS agent project (or start fresh with npx create-eliza-app)
• An AgentTrust API key (get one free)
• TypeScript familiarity

Step 1: Project Structure

Create a new directory for your plugin:

eliza-plugin-agenttrust/
├── src/
│   ├── index.ts
│   ├── actions/
│   │   └── checkReputation.ts
│   └── types.ts
├── package.json
└── tsconfig.json

Step 2: Define the Plugin Interface

// src/types.ts
export interface ReputationScore {
  address: string;
  score: number;
  grade: string;
  factors: {
    age: number;
    volume: number;
    successRate: number;
    diversity: number;
    consistency: number;
    endorsements: number;
    collaboration: number;
  };
  updatedAt: string;
}

export interface CheckReputationConfig {
  apiKey: string;
  baseUrl?: string;
}

Step 3: Create the Action

The action is what ElizaOS agents can invoke via natural language. It calls the AgentTrust API and returns a formatted score.

// src/actions/checkReputation.ts
import { Action, IAgentRuntime, Memory, State } from "@elizaos/core";

export const checkReputationAction: Action = {
  name: "CHECK_WALLET_REPUTATION",
  description: "Check an Ethereum wallet's on-chain reputation score",
  examples: [
    ["Check 0x742d35Cc6634C0532925a3b844Bc9e7595f12bD18"],
    ["What's the trust score of vitalik.eth?"],
    ["Is 0x1234... safe to transact with?"],
  ],
  validate: async (runtime: IAgentRuntime) => {
    return !!runtime.getSetting("AGENTTRUST_API_KEY");
  },
  handler: async (
    runtime: IAgentRuntime,
    message: Memory,
    state: State
  ): Promise => {
    const address = extractAddress(message.content.text);
    if (!address) return "No wallet address found in your message.";

    const apiKey = runtime.getSetting("AGENTTRUST_API_KEY");
    const res = await fetch(
      `https://agent-trust-score.web.app/api/score/${address}`,
      { headers: { "X-API-Key": apiKey } }
    );

    if (res.status === 402) {
      return "Score not available. Please add credits.";
    }

    const data = await res.json();
    return formatScore(data);
  },
};

Step 4: Register the Plugin

// src/index.ts
import { Plugin } from "@elizaos/core";
import { checkReputationAction } from "./actions/checkReputation";

export const agentTrustPlugin: Plugin = {
  name: "agent-trust",
  description: "On-chain wallet reputation via AgentTrust",
  actions: [checkReputationAction],
  evaluators: [],
  providers: [],
};

Step 5: Install in Your Agent

Add the plugin to your ElizaOS agent configuration:

// agent.config.ts
import { Agent } from "@elizaos/core";
import { agentTrustPlugin } from "./plugins/agentTrust";

const agent = new Agent({
  name: "trading-agent",
  plugins: [
    agentTrustPlugin,
    // other plugins...
  ],
  settings: {
    AGENTTRUST_API_KEY: process.env.AGENTTRUST_API_KEY,
  },
});

await agent.start();

Step 6: Test It

Once the agent is running, you can interact with it:

User: "Check 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
Agent: "Wallet 0x8dA6...6045 has a score of 92 (AAA).
        Ultra Reliable. 7+ years of activity,
        $50M+ volume, 99.8% success rate."

Beyond Basic Checking

Once your plugin works, extend it with:

• x402 payment support — Let agents pay for scores automatically
• Threshold-based actions — Auto-reject transactions below a configurable score
• Batch checking — Score multiple addresses in one call
• Score caching — Reduce API calls by caching results locally

For the full ElizaOS plugin source code, check the AgentTrust GitHub repository. Learn more about top AI agent tools for crypto including ElizaOS and AgentTrust.