Google Calendar

CommunicationPublisher: Google

Route Google Calendar MCP traffic through Formal to control and log what AI agents do in Google Calendar:

Block risky tools, such as delete_event.
Mask sensitive data in tool results, such as emails in list_events responses.
Keep credentials at the Connector, so users and agents never see Google Calendar tokens.
Log every tool call with the user, the MCP client and its parameters.

0. Prepare your Connector

The Connector needs an MCP listener and a hostname with wildcard DNS and TLS. Set them up once by following Deploy the Connector. Every MCP server reuses them.

1. Add Google Calendar MCP server to your Resources

UI
Terraform
Pulumi
API

Open the Admin Catalog and click Add MCP.
Select the Google Calendar template.
Enter a DNS-label Name, such as google-calendar.
Choose the Space containing your Connector, such as default.
Configure upstream authentication as described below, then save.

If no Connector is in the selected Space, the Configuration tab shows MCP clients can’t connect directly yet. The reason reads: No Connector is in this server's Space.

Set space_id to the ID of the Space containing your Connector.

resource "formal_resource" "google_calendar" {
  name                    = "google-calendar"
  technology              = "mcp"
  hostname                = "calendarmcp.googleapis.com"
  space_id                = "<SPACE_ID>"
  native_users_v3_enabled = true
  port                    = 443
  tags = {
    "mcp-endpoint" = "/mcp/v1"
  }
}

resource "formal_resource_oauth_settings" "google_calendar" {
  resource_id = formal_resource.google_calendar.id
}

Set spaceId to the ID of the Space containing your Connector.

import * as formal from "@formalco/pulumi";

const resource = new formal.Resource("mcp", {
  name: "google-calendar",
  technology: "mcp",
  hostname: "calendarmcp.googleapis.com",
  port: 443,
  spaceId: "<SPACE_ID>",
  tags: { "mcp-endpoint": "/mcp/v1" },
  nativeUsersV3Enabled: true,
});

new formal.ResourceOauthSettings("mcpOAuth", {
  resourceId: resource.id,
});

Create a Resource with the MCP endpoint and its Space ID.

export FORMAL_API_KEY="<YOUR_API_KEY>"
RESOURCE_RESPONSE=$(curl --fail --silent --show-error \
  --request POST \
  https://api.formal.ai/core.v1.ResourceService/CreateResource \
  --header "x-api-key: ${FORMAL_API_KEY}" \
  --header "Content-Type: application/json" \
  --data-binary @- <<JSON
  {
    "name": "google-calendar",
    "hostname": "calendarmcp.googleapis.com",
    "port": 443,
    "technology": "mcp",
    "spaceId": "<SPACE_ID>",
    "tags": [
      {
        "key": "mcp-endpoint",
        "value": "/mcp/v1"
      }
    ]
  }
JSON
)
RESOURCE_ID=$(printf '%s' "${RESOURCE_RESPONSE}" | jq -r '.resource.id')
curl --fail --silent --show-error \
  --request POST \
  https://api.formal.ai/core.v1.ResourceService/CreateResourceOAuthSettings \
  --header "x-api-key: ${FORMAL_API_KEY}" \
  --header "Content-Type: application/json" \
  --data-binary @- <<JSON
  {
    "resourceId": "${RESOURCE_ID}"
  }
JSON

2. Setup Authentication

Linked Accounts (Recommended)
Shared Credentials
Pass Through

Each user links their own Google Calendar account once in the Employee Catalog, and the Connector sends that user’s token to Google Calendar.

Linked Accounts selected under How does Formal authenticate to this resource?

Google Calendar doesn’t support Formal’s App, so register your own OAuth app.See Google Calendar OAuth documentation and register an app.

Configure the project

Enable the Calendar API and Calendar MCP API, then configure Google Auth Platform > Branding.

Choose scopes

Open Data Access > Add or Remove Scopes, add the required scopes, and click Update, then Save.

Create the client

Open Google Auth Platform > Clients, click Create Client, select Web application, and enter a Name.

Set the callback

Under Authorized redirect URIs, click + Add URI and paste Formal’s Redirect URI into URIs.

Get credentials

Select Use this client for an AI-powered agent, click Create, and copy the Client ID and Client Secret.

Enter the app in Formal

UI
Terraform
Pulumi
API

Back in the Admin Catalog, enter the Client ID and Client secret, then save. Users then link their accounts on the Google Calendar server’s page in the Employee Catalog.

Your OAuth App selected in the Admin Catalog, with the Redirect URI, Client ID and Client secret fields

Use these OAuth settings instead of the ones from step 1.

variable "google_calendar_oauth_client_secret" {
  type      = string
  sensitive = true
}

resource "formal_resource_oauth_settings" "google_calendar" {
  resource_id              = formal_resource.google_calendar.id
  upstream_oauth_mode      = "pre_registered"
  client_id                = "<YOUR_CLIENT_ID>"
  client_secret_wo         = var.google_calendar_oauth_client_secret
  client_secret_wo_version = 1
}

Use these OAuth settings instead of the ones from step 1. Store the secret with pulumi config set --secret googleCalendarOauthClientSecret.

import * as pulumi from "@pulumi/pulumi";

const config = new pulumi.Config();

new formal.ResourceOauthSettings("mcpOAuth", {
  resourceId: resource.id,
  upstreamOauthMode: "pre_registered",
  clientId: "<YOUR_CLIENT_ID>",
  clientSecret: config.requireSecret("googleCalendarOauthClientSecret"),
});

Use this call instead of the CreateResourceOAuthSettings call from step 1. The OAuth app is fixed at creation.

curl --fail --silent --show-error \
  --request POST \
  https://api.formal.ai/core.v1.ResourceService/CreateResourceOAuthSettings \
  --header "x-api-key: ${FORMAL_API_KEY}" \
  --header "Content-Type: application/json" \
  --data-binary @- <<JSON
  {
    "resourceId": "${RESOURCE_ID}",
    "upstreamOauthMode": "pre_registered",
    "clientId": "<YOUR_CLIENT_ID>",
    "clientSecret": "<YOUR_CLIENT_SECRET>"
  }
JSON

3. Route Endpoint traffic

Auth is managed at the Connector level when you use Linked Accounts or Shared Credentials, so the Endpoint needs to forward the MCP traffic to it. Laptops and VMs with the Formal Endpoint keep using https://calendarmcp.googleapis.com/mcp/v1, and a network rule sends that traffic to the Connector.

UI
Terraform
Pulumi
API

Go to Network Rules and create a rule named google-calendar-mcp.
Paste this expression, set the rule to Active, then save:

{
  "condition": {
    "pre_tcp": process.is_agent,
    // Every MCP server added to Formal: process.is_agent && resource.technology == "mcp"
    "pre_tls": process.is_agent && hostname == "calendarmcp.googleapis.com",
    "post_tls": true
  },
  "outputs": {
    "forward_to_connector": true
  }
}

resource "formal_network_rule" "google_calendar_mcp" {
  name        = "google-calendar-mcp"
  description = "Forward Google Calendar MCP traffic from agents to the Connector"
  status      = "active"

  # Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp"
  cel_expression = <<-EOT
    {
      "condition": {
        "pre_tcp": process.is_agent,
        "pre_tls": process.is_agent && hostname == "calendarmcp.googleapis.com",
        "post_tls": true
      },
      "outputs": {
        "forward_to_connector": true
      }
    }
  EOT
}

import * as formal from "@formalco/pulumi";

new formal.NetworkRule("googleCalendarMcp", {
  name: "google-calendar-mcp",
  description: "Forward Google Calendar MCP traffic from agents to the Connector",
  status: "active",
  // Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp"
  celExpression: `
    {
      "condition": {
        "pre_tcp": process.is_agent,
        "pre_tls": process.is_agent && hostname == "calendarmcp.googleapis.com",
        "post_tls": true
      },
      "outputs": {
        "forward_to_connector": true
      }
    }
  `,
});

export FORMAL_API_KEY="<YOUR_API_KEY>"
# Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp"
CEL_EXPRESSION=$(cat <<'CEL'
{
  "condition": {
    "pre_tcp": process.is_agent,
    "pre_tls": process.is_agent && hostname == "calendarmcp.googleapis.com",
    "post_tls": true
  },
  "outputs": {
    "forward_to_connector": true
  }
}
CEL
)
jq -n --arg cel "${CEL_EXPRESSION}" '{
  name: "google-calendar-mcp",
  description: "Forward Google Calendar MCP traffic from agents to the Connector",
  status: "active",
  celExpression: $cel
}' | curl --fail --silent --show-error \
  --request POST \
  https://api.formal.ai/core.v1.DesktopService/CreateDesktopRoutingRule \
  --header "x-api-key: ${FORMAL_API_KEY}" \
  --header "Content-Type: application/json" \
  --data-binary @-

The rule matches known agents only. See Identity headers.Cloud agents such as Claude, ChatGPT and Cursor Cloud Agents don’t run the Endpoint. Point them at this server’s Connector address, https://google-calendar.<connector-hostname>/mcp. Find it in the Admin Catalog: open Google Calendar, then copy Connector address on the Configuration tab.

4. Create policies

Tools

The Admin Catalog lists these tools for Google Calendar:

Tool	Description
`list_calendars`	List calendars available to the user.
`list_events`	List events in a date range.
`get_event`	Retrieve a calendar event.
`create_event`	Create a calendar event.
`update_event`	Update a calendar event.
`delete_event`	Delete a calendar event.
`find_free_time`	Find shared availability for attendees.
`respond_to_event`	Accept, decline, or tentatively accept an invitation.

Policies examples

Block a tool
Mask a tool's output

This policy blocks the tools that change data, so agents can only read Google Calendar.

package formal.v2

import future.keywords.if
import future.keywords.in

write_tools := {
  "create_event",
  "update_event",
  "delete_event",
  "respond_to_event",
}

request := {
  "action": "block",
  "type": "block_with_custom_message",
  "message": "Writing to Google Calendar is not allowed.",
} if {
  input.resource.name == "google-calendar"
  input.mcp.method == "tools/call"
  input.mcp.tool_name in write_tools
}

This policy replaces email addresses in results returned by list_events, get_event, and list_calendars.

package formal.v2

import future.keywords.if
import future.keywords.in

email_pattern := `[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}`

response := {
  "action": "rewrite",
  "body": regex.replace(input.http.body, email_pattern, "[REDACTED-EMAIL]"),
  "reason": "Mask emails in Google Calendar results",
} if {
  input.resource.name == "google-calendar"
  input.mcp.tool_name in {"list_events", "get_event", "list_calendars"}
  regex.match(email_pattern, input.http.body)
}

See MCP resources for the input.mcp fields and Rewrite Action for body rewrites.

5. Check the logs

Open Logs and search for resource.name:google-calendar. Each Google Calendar tool call is one request log with the user, the MCP client and the tool. Open a log to see its tool parameters and the policies it triggered. A blocked write shows the block policy and its message. A masked search shows the rewrite policy.See Logs for search syntax and filters.

Troubleshooting

The agent relays: Formal has no current google-calendar sign-in for you. Link or re-link your google-calendar account in Formal…Cause: The user never linked Google Calendar, or the token expired and couldn’t be refreshed.Fix: Open the server in the Employee Catalog and link Google Calendar again.

The agent says Google Calendar rejected your credentials

The agent relays: google-calendar rejected your credentials. Link or re-link your google-calendar account in Formal…Cause: Google Calendar no longer accepts the linked token, for example after the user revoked access in Google Calendar.Fix: Link Google Calendar again from the Employee Catalog.

Laptop traffic doesn't appear in Logs

Cause: The Endpoint isn’t running, or the network rule doesn’t match the client.Fix: Check the Endpoint is connected. The rule above only matches known agents. Other clients, such as a browser, reach Google Calendar directly unless the rule also matches them. See Network rules.

MCP clients can't connect directly yet

Cause: The Configuration tab lists the reason, most often No Connector is in this server's Space.Fix: Edit the server and choose the Space containing its Connector.

Getting Started

Example Use Cases

AI Governance

Configuring Formal

Integrations

Configuration

0. Prepare your Connector

1. Add Google Calendar MCP server to your Resources

2. Setup Authentication

3. Route Endpoint traffic

4. Create policies

Tools

Policies examples

5. Check the logs

Troubleshooting

Next Steps

MCP Gateway

All MCP servers

​0. Prepare your Connector

​1. Add Google Calendar MCP server to your Resources

​2. Setup Authentication

​3. Route Endpoint traffic

​4. Create policies

​Tools

​Policies examples

​5. Check the logs

​Troubleshooting

​Next Steps

MCP Gateway

All MCP servers

0. Prepare your Connector

1. Add Google Calendar MCP server to your Resources

2. Setup Authentication

3. Route Endpoint traffic

4. Create policies

Tools

Policies examples

5. Check the logs

Troubleshooting

Next Steps