Using Pipelock with Google ADK#

Pipelock wraps MCP servers used by Google ADK agents as a stdio proxy, scanning
every request and response for credential leaks, prompt injection, and tool
description poisoning. This guide covers McpToolset with StdioConnectionParams
and Docker Compose deployment.

Quick Start#

# 1. Install pipelock
go install github.com/luckyPipewrench/pipelock/cmd/pipelock@latest

# 2. Generate a config (or copy a preset)
pipelock generate config --preset balanced > pipelock.yaml

# 3. Verify
pipelock version

from google.adk.agents import Agent
from google.adk.tools import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from mcp import StdioServerParameters

filesystem_toolset = McpToolset(
    connection_params=StdioConnectionParams(
        server_params=StdioServerParameters(
            command="pipelock",
            args=[
                "mcp", "proxy",
                "--config", "pipelock.yaml",
                "--",
                "npx", "-y", "@modelcontextprotocol/server-filesystem", "/workspace"
            ],
        )
    )
)

agent = Agent(
    model="gemini-2.0-flash",
    name="research_agent",
    instruction="You help users research information using available tools.",
    tools=[filesystem_toolset],
)

That's it. Pipelock intercepts all MCP traffic between the ADK agent and the
filesystem server, scanning in both directions.

How It Works#

ADK Agent <--> pipelock mcp proxy <--> MCP Server
 (client) (scan both ways) (subprocess)

Pipelock scans three things:

Outbound requests. Catches credentials leaking through tool arguments
(API keys, tokens, private key material).
Inbound responses. Catches prompt injection in tool results.
Tool descriptions. Catches poisoned tool definitions and mid-session
rug-pull changes.

Integration Patterns#

Pattern A: Single MCP Server with Runner#

The standard ADK pattern using Runner for agent execution:

import asyncio
from google.adk.agents import Agent
from google.adk.runners import Runner
from google.adk.sessions import InMemorySessionService
from google.adk.tools import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from google.genai import types
from mcp import StdioServerParameters

async def main():
    toolset = McpToolset(
        connection_params=StdioConnectionParams(
            server_params=StdioServerParameters(
                command="pipelock",
                args=[
                    "mcp", "proxy",
                    "--config", "pipelock.yaml",
                    "--",
                    "npx", "-y", "@modelcontextprotocol/server-filesystem", "/workspace"
                ],
            )
        )
    )

    agent = Agent(
        model="gemini-2.0-flash",
        name="file_agent",
        instruction="You analyze files in the workspace.",
        tools=[toolset],
    )

    runner = Runner(
        agent=agent,
        app_name="pipelock_demo",
        session_service=InMemorySessionService(),
    )

    session = await runner.session_service.create_session(
        app_name="pipelock_demo", user_id="user1"
    )

    content = types.Content(
        role="user",
        parts=[types.Part(text="List all files in the workspace")]
    )

    async for event in runner.run_async(
        user_id="user1", session_id=session.id, new_message=content
    ):
        if event.is_final_response():
            print(event.content.parts[0].text)

asyncio.run(main())

Pattern B: Multiple MCP Servers#

Wrap each server independently with its own Pipelock proxy:

from google.adk.agents import Agent
from google.adk.tools import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from mcp import StdioServerParameters

filesystem = McpToolset(
    connection_params=StdioConnectionParams(
        server_params=StdioServerParameters(
            command="pipelock",
            args=["mcp", "proxy", "--config", "pipelock.yaml", "--",
                  "npx", "-y", "@modelcontextprotocol/server-filesystem", "/workspace"],
        )
    )
)

database = McpToolset(
    connection_params=StdioConnectionParams(
        server_params=StdioServerParameters(
            command="pipelock",
            args=["mcp", "proxy", "--config", "pipelock.yaml", "--",
                  "python", "-m", "mcp_server_sqlite", "--db", "/data/app.db"],
        )
    )
)

agent = Agent(
    model="gemini-2.0-flash",
    name="multi_tool_agent",
    instruction="You work with files and databases.",
    tools=[filesystem, database],
)

Pattern C: Mixed Transports#

Wrap stdio servers with Pipelock. Remote servers connect directly and are not
covered by the stdio proxy:

from google.adk.agents import Agent
from google.adk.tools import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import (
    StdioConnectionParams,
    SseConnectionParams,
)
from mcp import StdioServerParameters

# Local server: wrap with pipelock
local = McpToolset(
    connection_params=StdioConnectionParams(
        server_params=StdioServerParameters(
            command="pipelock",
            args=["mcp", "proxy", "--config", "pipelock.yaml", "--",
                  "npx", "-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
        )
    )
)

# Direct remote server: NOT scanned by Pipelock.
# To scan this path, expose the remote endpoint through:
# pipelock mcp proxy --upstream https://api.example.com/mcp/sse
remote = McpToolset(
    connection_params=SseConnectionParams(url="https://api.example.com/mcp/sse")
)

agent = Agent(
    model="gemini-2.0-flash",
    name="hybrid_agent",
    instruction="You use local and remote tools.",
    tools=[local, remote],
)

Note: Direct SseConnectionParams / HTTP MCP connections go straight to the
remote endpoint and bypass Pipelock. To scan remote MCP traffic you have two
options:

pipelock mcp proxy --upstream https://api.example.com/mcp/sse registers
Pipelock as a stdio MCP server that bridges to the remote endpoint. Use this
when the upstream needs no client-supplied HTTP headers, since the stdio
bridge does not have a transparent path for the client's Authorization or
other custom headers.
HTTP reverse proxy mode (pipelock run --mcp-listen ADDR --mcp-upstream URL)
preserves request headers through to the upstream. Use this when the upstream
requires per-request Authorization or other client-supplied headers, or
when the client needs an HTTP MCP URL.

For outbound HTTP traffic from your agent code (API calls, web fetches), route
those through pipelock run as a fetch proxy. See the
HTTP fetch proxy section below.

Pattern D: Sub-Agents#

ADK supports hierarchical agent architectures. Each sub-agent can have its own
Pipelock-wrapped MCP servers with different security configs:

from google.adk.agents import Agent
from google.adk.tools import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from mcp import StdioServerParameters

researcher = Agent(
    model="gemini-2.0-flash",
    name="researcher",
    instruction="You research topics using available tools.",
    tools=[
        McpToolset(
            connection_params=StdioConnectionParams(
                server_params=StdioServerParameters(
                    command="pipelock",
                    args=["mcp", "proxy", "--config", "pipelock-warn.yaml", "--",
                          "npx", "-y", "@modelcontextprotocol/server-fetch"],
                )
            )
        ),
    ],
)

writer = Agent(
    model="gemini-2.0-flash",
    name="writer",
    instruction="You write reports. Delegate research to the researcher.",
    tools=[
        McpToolset(
            connection_params=StdioConnectionParams(
                server_params=StdioServerParameters(
                    command="pipelock",
                    args=["mcp", "proxy", "--config", "pipelock-strict.yaml", "--",
                          "npx", "-y", "@modelcontextprotocol/server-filesystem", "/output"],
                )
            )
        ),
    ],
    sub_agents=[researcher],
)

Docker Compose#

Network-isolated deployment where the agent container has no direct internet
access:

networks:
  pipelock-internal:
    internal: true
    driver: bridge
  pipelock-external:
    driver: bridge

services:
  pipelock:
    # Pin to a specific version for production. See https://github.com/luckyPipewrench/pipelock/releases for available tags.
    image: ghcr.io/luckypipewrench/pipelock:latest
    networks:
      - pipelock-internal
      - pipelock-external
    command: ["run", "--listen", "0.0.0.0:8888", "--config", "/config/pipelock.yaml"]
    volumes:
      - ./pipelock.yaml:/config/pipelock.yaml:ro
    healthcheck:
      test: ["/pipelock", "healthcheck"]
      interval: 10s
      timeout: 3s
      start_period: 5s
      retries: 3

  adk-agent:
    build: .
    networks:
      - pipelock-internal
    environment:
      - GOOGLE_API_KEY=${GOOGLE_API_KEY}
      - PIPELOCK_FETCH_URL=http://pipelock:8888/fetch
    depends_on:
      pipelock:
        condition: service_healthy

The agent container can only reach the pipelock service. All HTTP traffic goes
through the fetch proxy. MCP servers running as subprocesses inside the agent
container are wrapped with pipelock mcp proxy as shown above.

You can also generate this template with:

pipelock generate docker-compose --agent generic

HTTP Fetch Proxy#

For scanning HTTP traffic from ADK agents (web fetches, API calls), run Pipelock
as a fetch proxy:

pipelock run --config pipelock.yaml

Configure your agent to route HTTP requests through http://localhost:8888/fetch:

import requests

def fetch_through_pipelock(url: str) -> str:
    resp = requests.get(
        "http://localhost:8888/fetch",
        params={"url": url},
        headers={"X-Pipelock-Agent": "adk-research"},
        timeout=30,
    )
    resp.raise_for_status()
    data = resp.json()
    if data.get("blocked"):
        raise RuntimeError(f"Pipelock blocked request: {data.get('block_reason')}")
    return data.get("content", "")

TLS Interception#

When using pipelock as an HTTP forward proxy (HTTPS_PROXY), CONNECT tunnels
are opaque by default: pipelock only sees the hostname, not the request body or
response content. Enabling TLS interception closes this gap by performing a MITM
on HTTPS connections, giving you full DLP on request bodies and response
injection detection through CONNECT tunnels.

To enable it:

Generate a CA and enable TLS interception (see the TLS Interception Guide)
Trust the CA in your Python environment:

export SSL_CERT_FILE=~/.pipelock/ca.pem
# Or for requests/httpx specifically:
export REQUESTS_CA_BUNDLE=~/.pipelock/ca.pem

MCP proxy mode (stdio wrapping) does not require TLS interception. It scans
traffic in both directions without certificates.

Choosing a Config#

Config	Action	Best For
`balanced`	warn (default)	Recommended starting point (`--preset balanced`)
`strict`	block (default)	High-security, production (`--preset strict`)
`generic-agent.yaml`	warn (default)	Agent-specific tuning (copy from `configs/`)
`claude-code.yaml`	block (default)	Unattended coding agents (copy from `configs/`)

Start with balanced to log detections without blocking. Review the logs,
tune thresholds, then switch to strict for production.

Troubleshooting#

MCP server not starting#

Verify the command works without Pipelock first:

npx -y @modelcontextprotocol/server-filesystem /tmp

Then wrap it:

pipelock mcp proxy -- npx -y @modelcontextprotocol/server-filesystem /tmp

Seeing Pipelock output#

Pipelock logs to stderr. To see real-time output during development:

echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | \
  pipelock mcp proxy --config pipelock.yaml -- npx -y @modelcontextprotocol/server-filesystem /tmp

False positives#

Switch to warn mode to see what's being flagged without blocking:

response_scanning:
  action: warn
mcp_input_scanning:
  action: warn
mcp_tool_scanning:
  action: warn

Review stderr output, then tighten thresholds.

Config file not found#

Use absolute paths if relative paths don't resolve:

McpToolset(
    connection_params=StdioConnectionParams(
        server_params=StdioServerParameters(
            command="pipelock",
            args=["mcp", "proxy", "--config", "/etc/pipelock/config.yaml", "--",
                  "npx", "-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
        )
    )
)