Connect
Optimize
Secure
MCP Gateway
MCP Gateway
for Vertex AI Agents
One MCP gateway to connect Vertex AI to 310+ enterprise SaaS apps. No auth hassle. Token-efficient by design. Security and governance built-in.
What is an MCP gateway?
An MCP gateway (also called an MCP aggregator) is a single endpoint that connects an AI agent to multiple
MCP servers via the open Model Context Protocol (opens in new tab).
Some gateways act as proxies, routing traffic to MCP servers customers operate themselves. Others provide the
underlying MCP servers as a managed service.
StackOne is the managed kind. We provide pre-built MCP servers for 310+ enterprise SaaS apps,
including ones with no official MCP server today. For each app you connect, StackOne provides the MCP protocol
layer, the SaaS API integration, action coverage, and the auth orchestration framework. Authentication is
configured per app per organization — your team registers OAuth credentials with the SaaS provider, links them
in StackOne, and end users then authorize access through that flow. Once set up, the agent reaches every
connected app through one URL, with token storage, refresh, and per-user scoping handled by StackOne.
StackOne's MCP gateway — SOC2, HIPAA, CCPA, and GDPR compliant — bundles 310+ pre-built SaaS integrations exposing 20,000+ actions, all reachable from your Vertex AI agent through one URL.
Act across all your apps
from inside Vertex AI
One MCP gateway, every enterprise SaaS your Vertex AI agent
could ever need to act on.
Coverage
310+ connectors.
20,000+ tested actions.
Every action is built and maintained by StackOne, tested against the live API, and updated when vendors change their endpoints.
Browse all connectors
Trust
Auth & governance,
simplified.
StackOne handles OAuth, API keys, refresh, and scopes for every connector, giving enterprise IT full control through auth configs in a multi-tenant setup.
Agent Auth
Performance
Agent context window,
managed.
Tool Discovery and Code Mode keep your Vertex AI agent's context lean — only relevant actions, no raw response noise. Sharper agents, lower token costs.
Tools Discovery
Security
Agent security,
built in.
Defender scans every MCP tool response for prompt injection in real time. Up to 97.44%¹ detection, 0.2% false positives. SOC2, HIPAA, CCPA, GDPR compliant.
Prompt Injection Defense¹ Jayavibhav test, 65,000 samples.
Connect Vertex AI
to more apps in 4 steps
From auth config to first agent tool call in 5 minutes.
1
Wire StackOne as an MCPToolset in your ADK agent.
In Agent Development Kit (ADK) Python, wrap the StackOne gateway URL in MCPToolset and pass it as a tool on your LlmAgent. Deploy via Agent Engine — available to every agent in your GCP project.
Python — ADK Agent
from google.adk.agents import LlmAgent
from google.adk.tools.mcp_tool import (
MCPToolset, StreamableHTTPConnectionParams,
)
stackone = MCPToolset(
connection_params=StreamableHTTPConnectionParams(
url="https://api.stackone.com/mcp",
headers={"Authorization": f"Bearer {STACKONE_TOKEN}"},
)
)
agent = LlmAgent(
model="gemini-2.5-flash",
name="enterprise_agent",
tools=[stackone],
)
2
Connect each SaaS integration in StackOne.
OAuth or API key per app, done once in your dashboard. Tokens stay server-side.
3
Scope agent actions.
Read-only, specific objects, or per-role exposure. Toggle from the StackOne dashboard.
List records (enabled)
Get record (enabled)
Read related (enabled)
Update record (disabled)
Delete record (disabled)
4
Let your Vertex AI agent call StackOne in plain English.
StackOne maps the agent's tool call to the right action in the right system. Done.
"Sync this week's Salesforce opportunities into BigQuery and open a Linear ticket for any deal blocking the Q3 forecast."
salesforce_list_opportunities
Completed
linear_create_issue
Completed
team: Revenue Operations
priority: high
result: REV-512 created
Synced 38 Salesforce opportunities to BigQuery. Filed REV-512 for the 4 deals blocking Q3.
Get Vertex AI
to do more across your stack
Cross-app workflows your Vertex AI agent now runs in seconds instead of click-throughs.
Customer 360
> Pull Salesforce account context and join it with BigQuery product usage for the next-best action.
HR & Workforce
> Reconcile Workday hires with their GitHub access in seconds.
Finance & Billing
> Reconcile Stripe revenue with the NetSuite GL for month-end close.
Engineering & DevOps
> Open a Linear ticket from a Sentry alert and notify the on-call channel.
Connect any Enterprise AI Agent
to the StackOne MCP Gateway
Same 310+ MCP servers. Same agent context. Pick yours.
Frequently Asked Questions
Vertex AI agents consume external MCP servers through the Agent Development Kit (ADK). In a few lines of Python, wrap the StackOne gateway URL in an
MCPToolset with StreamableHTTPConnectionParams, pass it as a tool on your LlmAgent, and deploy via Agent Engine. 310+ pre-built SaaS connectors are reachable through that single toolset. Full walkthrough in the ADK MCP tools docs. Now part of the Gemini Enterprise Agent Platform.An MCP gateway (also called an MCP aggregator) is a single endpoint that connects an AI agent to multiple MCP servers via the Model Context Protocol. Some gateways route traffic to MCP servers customers operate themselves; others provide the MCP servers as a managed service. StackOne is the managed kind — we provide pre-built MCP servers for 310+ enterprise SaaS apps, including ones with no official MCP server today. Authentication is configured per app per organization: your team registers OAuth credentials with the SaaS provider, links them in StackOne, and end users authorize access through that flow. Once set up, the agent reaches every connected app through one URL.
Vertex AI agents can access enterprise SaaS like Salesforce, HubSpot, Workday, Greenhouse, BambooHR, Stripe, NetSuite, Ramp, GitHub, Linear, Sentry, and Datadog through the StackOne MCP gateway — 310+ pre-built connectors in total. StackOne extends Vertex AI beyond Google's first-party MCP services (BigQuery, Maps, Cloud SQL) into operational SaaS. New connectors ship continuously, and you can build custom ones with AI Integration Builder. See all connectors.
Google's first-party MCP servers cover Google-owned data (BigQuery, Maps, Cloud SQL via MCP Toolbox, plus Apigee adapters). StackOne adds the other 310+ operational SaaS — every app reachable through one
MCPToolset instead of one per app, auth managed once in the dashboard, and tool definitions loaded only when relevant to the prompt.Credentials sit at three layers: your StackOne API token (embedded in the gateway URL passed to
StreamableHTTPConnectionParams headers, stored as a Secret Manager secret in your GCP project), SaaS connector credentials (server-side in your StackOne dashboard), and per-user OAuth or session tokens (server-side, scoped per user). StackOne stores OAuth tokens and API keys, refreshes them automatically, and only exposes the actions you've authorized to the agent.Skip the StackOne MCP gateway when any of these is true:
- Google's first-party MCP servers (BigQuery, Maps, Cloud SQL via MCP Toolbox) cover your apps
- You only use a handful of actions across a few apps
- You don't need multi-tenancy, per-user permissions, or per-action scoping
- Indirect prompt injection isn't a concern
- Your MCP provider already does tool discovery and server-side execution to keep the agent context lean
Connect All Your Apps to Vertex AI.
One MCP gateway, 310+ pre-built SaaS connectors. Set up in 5 minutes.