# MCP protocol versions

The **Protocol** column on MCP Inventory shows which version of the Model Context Protocol
each server actually negotiated with the tool that called it.

## Where the number comes from

The Sentilai shim observes the handshake between the AI tool and the local server and
reports the negotiated version. It is observed, not asserted — this is what the two ends
actually agreed on, not what the server's documentation claims.

A dash with a tooltip means no handshake has been observed yet: usually the server is
known only from a chat-request declaration or from Gateway traffic, with no shim in the
path.

## Why it matters

The protocol has changed meaningfully between versions, including in how tool calls are
framed and what a server may assert about itself. A server pinned to an old version is not
necessarily dangerous, but it is a signal worth having when you are deciding whether to
approve something.

It is also useful in reverse: if a server you expect to be governed shows no protocol at
all, the shim is probably not in its path, and your per-tool rules will not apply to it.

## What Sentilai enforces

The Gateway checks that the request's headers and body agree about which MCP method and
server are being addressed, and rejects requests where they do not. A mismatch is either a
broken client or an attempt to have the policy engine and the server read the same request
differently.