oceanalt-mcp

OceanAlt pre-payment check for AI agents: before your agent pays, ask whether the payment should proceed. Returns allow, review or decline with reasons and evidence.

from oceanalt_mcp import decide
r = decide("0xd90e2f925DA726b50C4Ed8D0Fb90Ad053324F31b", network="ethereum")
print(r["decision"])  # decline: a known mixer

Amazon Bedrock AgentCore payments

AgentCore calls pre_sign_policy before it signs a payment and signs only if the policy returns exactly True. Set this policy on the config of every AgentCore payments integration you want gated. Installing or importing this package changes nothing by itself.

Install this version and the SDK for your framework:

pip install "oceanalt-mcp==0.1.2" bedrock-agentcore strands-agents        # Strands
pip install "oceanalt-mcp==0.1.2" bedrock-agentcore langchain langgraph   # LangGraph

This client needs Python 3.8+ and has no third-party dependencies. The AgentCore SDK and the frameworks have their own requirements (Python 3.10+ for the versions verified below).

Strands:

from strands import Agent
from bedrock_agentcore.payments.integrations.strands import AgentCorePaymentsPlugin, AgentCorePaymentsPluginConfig
from oceanalt_mcp import agentcore_pre_sign_policy

config = AgentCorePaymentsPluginConfig(
    payment_manager_arn="arn:aws:...",
    user_id="user-123",
    payment_instrument_id="instrument-456",
    payment_session_id="session-789",
    pre_sign_policy=agentcore_pre_sign_policy,
)
agent = Agent(tools=[...], plugins=[AgentCorePaymentsPlugin(config)])

LangGraph (LangChain create_agent):

from langchain.agents import create_agent
from bedrock_agentcore.payments.integrations.langgraph import AgentCorePaymentsMiddleware, AgentCorePaymentsConfig
from oceanalt_mcp import agentcore_pre_sign_policy

config = AgentCorePaymentsConfig(payment_manager_arn="arn:aws:...", user_id="user-123",
                                 payment_instrument_id="instrument-456", payment_session_id="session-789",
                                 pre_sign_policy=agentcore_pre_sign_policy)
agent = create_agent(model=..., tools=[...], middleware=[AgentCorePaymentsMiddleware(config)])

What the policy checks: the payee address and network of each offer, and nothing else. It does not check the amount, the asset, the merchant's origin or any other payment condition, so True means every payee passed this check, not that the whole payment is approved.

How it decides:

• Returns True only when the request is an unambiguous x402 v1 request (JSON body, x402Version 1) or x402 v2 request (base64 Payment-Required header, x402Version 2, CAIP-2 networks), and OceanAlt answers allow for every payee offered in it.
• Returns False, so nothing is signed, for: MPP challenges, a request carrying both v1 and v2 requirements, any entry without a payee or network, a v2 network that is not a valid CAIP-2 id, a duplicate JSON key, base64 that is not strictly valid, a version that does not match, more than 10 offers, a decline or review, a timeout, an HTTP error and any other exception.
• Checks every offered payee, because AgentCore may pick any of them (a conservative choice). A repeated payee is looked up once. Each lookup times out after 8 seconds and the whole check after 20; both are arguments of the policy.
• Sends each offered payee address and its network to https://oceanalt.com/api/decide. Nothing else from the request is sent.
• The free tier needs no key. It has a monthly anonymous allowance and per-IP rate limits; agents behind one shared IP share them. When either is used up the policy returns False.

Verified against bedrock-agentcore 1.26.0 (strands-agents 1.64.0, langgraph 1.2.20) with a mock signer: 0 signer calls on decline, review, unreadable, ambiguous or MPP input, timeout and exception; 1 on allow. Not yet tested end to end in a live AWS account.

Free to use. Docs: https://oceanalt.com/en/api-docs · Hosted MCP server: https://oceanalt.com/api/mcp