langchain-mcps 0.1.0

MCPS (MCP Secure) integration for LangChain -- cryptographic identity and trust verification for AI agents.

langchain-mcps

MCPS (MCP Secure) integration for LangChain -- cryptographic identity and trust verification for AI agents.

Add zero-trust identity verification to any LangChain agent or chain with one line of code.

Install

pip install langchain-mcps

Quick Start

Callback Handler (recommended)

Attach to any LangChain agent or chain via callbacks:

from mcp_secure import generate_key_pair, create_passport, sign_passport
from langchain_mcps import MCPSCallbackHandler

# Generate keys and create a signed passport
authority_keys = generate_key_pair()
agent_keys = generate_key_pair()
passport = create_passport(
    name="my-agent",
    version="1.0.0",
    public_key=agent_keys["public_key"],
)
signed_passport = sign_passport(passport, authority_keys["private_key"])

# Create the handler
handler = MCPSCallbackHandler(
    passport=signed_passport,
    authority_public_key=authority_keys["public_key"],
    private_key=agent_keys["private_key"],  # optional: signs actions
)

# Use with any LangChain chain or agent
result = my_chain.invoke(
    {"question": "What is MCPS?"},
    config={"callbacks": [handler]},
)

# Check verification status and audit log
print(handler.is_verified)  # True
print(handler.audit_log)    # [{timestamp, event, action, ...}, ...]

Middleware Wrapper

Wrap any LangChain Runnable with a verification gate:

from langchain_mcps import with_mcps

secure_chain = with_mcps(my_chain, signed_passport, authority_keys["public_key"])
result = secure_chain.invoke({"question": "hello"})
# Raises PermissionError if passport is invalid, expired, or revoked

Features

• Identity verification -- ECDSA P-256 passport verification before any agent action
• Action signing -- cryptographically sign every chain/tool invocation
• Trust levels -- enforce minimum trust (L0 Unsigned through L4 Audited)
• Revocation checks -- optional live revocation via AgentSign Trust Authority
• Audit trail -- full log of verified/rejected events
• Replay protection -- nonce-based replay attack prevention
• Zero config -- works with any LangChain Runnable (chains, agents, tools)

Trust Levels

Level	Name	Meaning
L0	UNSIGNED	No verification
L1	IDENTIFIED	Agent has a passport
L2	VERIFIED	Passport signature verified
L3	SCANNED	Agent code passed OWASP scan
L4	AUDITED	Full security audit completed

API

MCPSCallbackHandler

Parameter	Type	Default	Description
passport	dict	required	Signed agent passport
authority_public_key	str	required	Trust Authority PEM public key
private_key	str	None	Agent PEM private key (for signing)
min_trust_level	int	1	Minimum trust level to accept
verify_revocation	bool	False	Check live revocation status
trust_authority	str	"https://agentsign.dev"	Trust Authority URL
on_verified	callable	None	Callback on successful verification
on_rejected	callable	None	Callback on failed verification
on_action	callable	None	Callback with signed action envelopes

with_mcps(chain, passport, authority_public_key, **kwargs)

Convenience wrapper. Returns an MCPSChainWrapper with .invoke(), .ainvoke(), .stream(), .batch().

Related

• mcp-secure -- Core MCPS Python library
• mcp-secure (npm) -- Core MCPS Node.js library
• AgentSign -- Zero Trust Engine for AI Agents
• OWASP Agentic AI -- Security framework for AI agents

License

MIT -- CyberSecAI Ltd