What is an MCP gateway?
Updated · DBShifts
Short answer
An MCP gateway is a proxy between AI agents (MCP clients) and the MCP servers they use. Every tool call passes through it, so one place decides which servers and tools each agent may use, checks the arguments, scans tool descriptions and results for injected instructions, applies limits and records the call.
Key facts
- An MCP gateway gives one enforcement point for many MCP servers instead of configuring each server separately.
- It can filter the tool list, so an agent is never offered a tool it is not allowed to call.
- It can check arguments, not just tool names — allowing create_issue only in one repository, for example.
- It treats tool descriptions and tool results as untrusted input, because the model reads both.
- It records every call with the agent that made it, which individual servers rarely do consistently.
In the glossary:MCP gateway
Why put a gateway in front of MCP servers
Each MCP server has its own authentication, its own logs and no idea which person an agent is acting for. With ten servers in use, nobody can answer which agent called what, and a dangerous tool is one config change away from every client. A gateway turns that into one policy, one log and one place to stop an agent.
What it should check on every call
Who is calling, and whether a rule allows this caller to reach this server. Whether the tool is allowed, and whether its arguments are. Whether the tool's description or the returned content carries instructions aimed at the model. Whether sensitive data is crossing in the arguments or the result. Whether the caller is inside its rate and loop limits. Then it writes the call down.
MCP gateway versus an AI agent gateway for data
An AI agent gateway for a database is itself an MCP server: it governs reads — tables, columns, masking, row caps. An MCP gateway governs calls to any MCP servers. They are complementary, and many teams run both.
Checklist
- 1
Deny by default for every agent and server
- 2
Offer each agent only the tools its rule allows
- 3
Argument rules on tools that write, delete or send
- 4
Scan tool descriptions and results for injected instructions
- 5
Mask sensitive data in arguments and results
- 6
Log every call and keep a per-agent stop switch
Common mistakes
Allowlisting servers but not tools
A server that offers both search and delete_repo is not safe to allow whole. The unit of permission is the tool, and often its arguments.
Scanning results but not descriptions
Tool poisoning arrives through descriptions, which are read before any result exists. They need the same scanning, every time the list is fetched.
How DBShifts does it
- DBShifts Agent Mesh is an MCP gateway as well as an A2A broker: every tools/call passes default-deny rules with tool allow/deny patterns and argument rules.
- It filters the tool list each caller sees, runs tool descriptions and results through the prompt-injection shield, and masks or blocks data by class in both arguments and results.
- Every call is traced with the chain that caused it, and a tool server can be paused in one click.
Questions people also ask
Is an MCP gateway the same as an API gateway?
It does a similar job for a different protocol, but it has to understand MCP: tool lists, tool calls and their arguments, and the fact that a model reads descriptions and results as instructions.
Can an MCP gateway run inside my network?
DBShifts can: a self-hosted Agent Mesh proxy runs next to your agents and tool servers and keeps their credentials in its own configuration.
Related questions
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