A2apay MCP Server

a2apay

Python client for a2apay.io — pay-per-call AI answers and persistent memory for autonomous agents. No account, no API key.

pip install a2apay-io          # free-tier only
pip install "a2apay-io[paid]"  # adds real payment support (eth-account)

(The PyPI distribution is named a2apay-io — an unrelated package already holds the bare a2apay name. The importable module is still a2apay.)

Quick start (free tier, zero setup)

Every call tries the free tier first automatically — 5 requests/day per caller, no wallet needed:

from a2apay import Agent

agent = Agent()
answer = agent.ask("What's 7 times 8?")
print(answer)

agent.remember("last_task", "processed invoice #4471", tags=["billing"])

With real payment (once the free tier is used up)

from a2apay import Agent

agent = Agent(private_key="0x...")  # or set A2APAY_PRIVATE_KEY
answer = agent.ask("What's 7 times 8?")

The wallet needs a small USDC balance on Base mainnet ($0.028/call). The private key is used only to sign a payment authorization locally — it is never sent anywhere.

Checkpoint / resume (task memory)

Write versioned, task-scoped state and read it back later — even from a different process. Each checkpoint() to the same key adds a new version rather than overwriting, and resume() always returns the latest.

from a2apay import Agent

agent = Agent(private_key="0x...")
agent.checkpoint("invoice-batch-7", key="status", value="processed rows 1-400")

# ...process dies, or a second process picks up later...

agent2 = Agent(private_key="0x...")  # same wallet
records = agent2.resume("invoice-batch-7")
print(records[0]["value"])  # "processed rows 1-400"

resume() always requires payment ($0.014/call) — there's no free tier for reads yet, so it needs a configured wallet even for your first call. checkpoint() follows the same free-tier-then-paid behavior as remember().

What this honestly does and doesn't do

• ask() returns a real AI-generated answer.
• remember() stores a flat key/value record with optional tags — this is simple text storage, not a document database. Values are stored as text.
• Falls back to a real payment only when the free tier returns a 402; if no private_key is configured at that point, it raises a clear A2ApayError rather than failing silently.
• Payment signing uses eth-account (maintained by the Ethereum Foundation ecosystem), implementing the real x402 "exact" EVM scheme per the x402 protocol spec.

MCP server

An MCP server (mcp_server.py) exposes ask and remember as MCP tools for any MCP-aware agent or framework (Claude Desktop, etc.):

pip install "a2apay-io[mcp]"
python mcp_server.py

Add to an MCP client config:

{
  "mcpServers": {
    "a2apay": {
      "command": "python",
      "args": ["/absolute/path/to/mcp_server.py"],
      "env": {"A2APAY_PRIVATE_KEY": "0x..."}
    }
  }
}

Honest scope note: remember is write-only — there's no memory read-back tool because the live API doesn't have a read-back route yet.

Full API reference

See a2apay.io/openapi.yaml for the underlying HTTP API this wraps.