agent402-google-adk

Google ADK (Agent Development Kit) tools for Agent402 - the open-source x402 + MCP server with 500+ pay-per-call web tools (browser, web search, OCR, PDFs, durable memory, pure-CPU utilities) and the cross-seller Smart Order Router that ranks tools across the x402 sellers Agent402 indexes.

Agent402 is the applied layer of Agentic Finance - agents that pay and get paid on their own over the two open wires, x402 and MPP (Machine Payments Protocol). Every paid endpoint answers both on the same 402; wallet-only tools take any payment-wrapped fetch (@x402/fetch, or a stock mppx fetch).

npm install agent402-google-adk @google/adk zod

Both peers are optional: install them only if you want real ADK FunctionTool instances. Without them, use agent402ToolSpecs() (below), which has no deps.

Quickstart

import { agent402Tools } from "agent402-google-adk";
import { LlmAgent } from "@google/adk";

// Free tier (proof-of-work auto-pay, no wallet)
const tools = await agent402Tools();

// Or, for wallet-required tools (browser, search, memory), supply an
// x402-wrapped fetch (e.g. @x402/fetch with your funded Base wallet):
// const tools = await agent402Tools({ fetch: payFetch });

const agent = new LlmAgent({
  name: "x402-agent",
  model: "gemini-2.0-flash",
  tools,
  instruction:
    "You have access to Agent402's 500+ web tools. Use agent402_find to " +
    "discover the right tool, then agent402_call to invoke it.",
});

What you get - four meta tools

The LLM picks tasks; the router ranks sellers; the caller handles payment.

| Tool | Purpose | |---|---| | agent402_find | Resolve a plain-language task to the best local Agent402 tool - slug, route, price, input schema, and a ready example. | | agent402_route | Cross-seller x402 router: rank tools across the x402 sellers Agent402 indexes (its own catalog plus the other sellers it discovers and crawls). Ranked by match score; ties break on health, then buyer count, then price. include: "external" excludes Agent402 itself, so it doubles as a neutral discovery API over the rest of the ecosystem. | | agent402_call | Call a tool by slug. Pays automatically: pure-CPU tools via proof-of-work; wallet-only via your x402 fetch. | | agent402_about | The Agent402 service manifest - payment options, capability map, MCP connector, trust signals. |

Why four meta tools and not one tool per slug? Registering 500+ individual tools blows past most agents' tool-budget and the LLM can't reason over hundreds of entries. Routing-as-discovery scales - the LLM describes the task, the router ranks the sellers that can serve it, the caller handles payment.

Framework-agnostic specs

If you'd rather not pull in @google/adk and zod (or you want to wrap the tools with your own factory), use the framework-agnostic export:

import { agent402ToolSpecs } from "agent402-google-adk";

const specs = agent402ToolSpecs();
// specs = [{ name, description, parametersJsonSchema, execute }, ...]
const result = await specs.find((s) => s.name === "agent402_route").execute({
  query: "ocr image",
  top: 3,
  include: "external",
});

Options

agent402Tools({
  baseUrl?: string,         // default: "https://agent402.tools"
  fetch?: typeof fetch,     // x402-wrapped fetch for wallet-required tools
  fetchImpl?: typeof fetch, // base fetch for unpaid lookups (default: global fetch)
})

agent402ToolSpecs() takes the same options.

Payment

Pure-CPU tools are free: agent402_call fetches a proof-of-work challenge and solves it in-process (a fraction of a second of CPU), so no wallet is needed. Wallet-only tools (network, browser, disk, live data) settle in USDC over x402 on whichever chain your wrapped fetch is funded for - Base, Solana, Polygon, Arbitrum, Monad, Celo, Avalanche, Sei, Optimism, Stellar or Algorand, plus USDG on Robinhood Chain (12 chains in all). Prices come from the live catalog at /api/pricing; never hardcode one.

License

MIT - part of Agent402.