THE GOVERNED MCP GATEWAY VISUAL GUIDE · MODEL CONTEXT PROTOCOL BY DIGITALAPI.AI

Visual guide 02

How MCP works.

MCP gives an AI application a standard way to connect to tools and data. Follow one request from the user to an external system and back.

6 MIN READSPEC 2025-11-25OFFICIAL SOURCES
ONE REQUESTMCP CONNECTION

MCP standardizes the connection between the AI app and the server.

Follow one request

Show me the open checkout incidents.

Connection setupRequestResult
01APP
Before the request

The AI app opens one connector for each service.

Each connector is an MCP client. It keeps a separate connection to one MCP server.

AI appIncident connectorMCP clientFile connectorMCP client
Incident serviceMCP serverFile serviceMCP server
One connector for each service
02LINK
Transport

The connector reaches a server here or over a network.

Local connections use standard input and output. Remote connections use Streamable HTTP.

Same computerAI appMCP serverstdio
Over a networkAI appMCP serverHTTP
03READY
Connection setup

The AI app and server agree on how to talk.

They exchange protocol versions and supported features before the app sends a request.

AI appMCP server
Version + features
Accepted version + capabilities
✓ Ready
04LIST
Discovery

The AI app asks what the server can do.

A server can offer actions, information, and templates. MCP calls them tools, resources, and prompts.

ActionsTools

Find incidents

InformationResources

Read a handbook

TemplatesPrompts

Review a support case

05USE
User request

The AI app chooses a tool and fills in its inputs.

For this request, it chooses Find incidents with checkout and open. The inputs must match the tool schema.

Selected toolFind incidentsincidents_search
service: checkoutstate: open
✓Inputs validmatches tool schema
06RUN
Server boundary

The server checks permission and does the work.

It validates the inputs, applies its access rules, and uses its own credentials to call the incident tracker.

Check permissionCall incident trackerRecord action
Blockedif permission fails
07BACK
Structured result

The result comes back to the AI app.

The app adds it to the conversation. The AI can now answer the user.

AI app

Here are the 3 open incidents.

Incident tracker3open incidents

Control points

Four checks before a tool runs.

The host, transport, and server each control a different part of the request.

Ask userHost
Verify identityTransport
Check permissionServer
Blocked
Run toolServer

Local stdio servers usually get credentials from their environment. MCP OAuth applies to HTTP connections.

The protocol boundary

MCP defines the connection. The host and server still make the decisions.

MCP DEFINES
  • Message format
  • Connection setup
  • Feature discovery
  • Calls and results
THE HOST DECIDES
  • How the model reasons
  • Which tool to select
  • When to ask the user
  • How to show the result
THE SERVER DECIDES
  • Which features exist
  • How tools run
  • What access is allowed
  • How systems are called

Official sources

Read the protocol.

This guide follows the stable MCP specification dated November 25, 2025.

  1. 01Architecture overview↗
  2. 02Understanding MCP servers↗
  3. 03Lifecycle specification↗
  4. 04Transport specification↗
  5. 05Authorization specification↗

MCP in production

One governed path for every agent and every tool.

See how Amelfi adds policy, credentials, and audit controls around MCP traffic.

See the productBook a walkthrough