Live 63 Actions

Cal.com MCP Server
for AI Agents

Q: What AI frameworks and AI clients does the StackOne Cal.com MCP server support?

The StackOne Cal.com MCP server supports both. MCP clients (paste-and-go apps): Claude Desktop, Claude Code, Cursor, VS Code, Goose. Agent frameworks (code SDKs you build with): OpenAI Agents SDK, Anthropic, Vercel AI, Google ADK, CrewAI, Pydantic AI, LangChain, LangGraph, Azure AI Foundry.

Connect your AI agent to StackOne's Cal.com MCP server and give it 63 MCP tools out of the box. Auth, tool execution, and security all managed.

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Cal.com MCP Server

Built by

StackOne

Coverage

63 Agent Actions

Create, read, update, and delete across Cal.com — and extend your agent's capabilities with custom actions.

MCP Actions → Build Actions →

Authentication

Agent Tool Authentication

Per-user OAuth in one call. Your Cal.com MCP server gets session-scoped tokens with zero credentials stored on your infra.

Agent Auth →

Security

Agent Protection

Every Cal.com tool response scanned for prompt injection in milliseconds — 88.7% accuracy, all running on CPU.

Prompt Injection Defense →

Performance

Max Agent Context. Min Cost.

Free up to 96% of your agent's context window to enhance reasoning and reduce cost, on every Cal.com call.

Tools Discovery →

What is the Cal.com MCP Server?

A Cal.com MCP server lets AI agents read and write Cal.com data through the Model Context Protocol — Anthropic's open standard for connecting LLMs to external tools. StackOne's Cal.com MCP server ships with 63 pre-built actions, fully extensible via the Connector Builder — plus managed authentication, prompt injection defense, observability, and agent execution runtime. Connect it from MCP clients like Claude Desktop, Claude Code, Cursor, Goose, and VS Code, or from agent frameworks like OpenAI Agents SDK, LangChain, and Vercel AI SDK.

All Cal.com MCP Tools

Every action from Cal.com's API, ready for your agent. Create, read, update, and delete — scoped to exactly what you need.

Current Users

Get Current User
Get information about the currently authenticated user
Update Current User
Update the authenticated user's profile

Bookings

Create Booking
Create a new booking
List Bookings
Get all bookings for the authenticated user
Get Booking
Get information about a specific booking

Booking Attendees

Add Booking Attendee
Add an attendee to an existing booking
Get Booking Attendees
Get all attendees for a booking
Get Booking Attendee
Get a specific attendee for a booking

Event Types

Create Event Type
Create a new event type
List Event Types
Get all event types for the authenticated user
Get Event Type
Get information about a specific event type
Update Event Type
Update an existing event type
Delete Event Type
Delete an event type

Schedules

Create Schedule
Create a new availability schedule
List Schedules
Get all schedules for the authenticated user
Get Schedule
Get information about a specific schedule
Update Schedule
Update an existing schedule
Delete Schedule
Delete a schedule

Reserved Slots

Get Reserved Slot
Get details of a reserved slot
Update Reserved Slot
Update a reserved slot
Delete Reserved Slot
Delete a slot reservation

Teams

Create Team
Create a new team
List Teams
Get all teams accessible to the authenticated user
Get Team
Get information about a specific team

Out Of Office Entrys

Create Out Of Office Entry
Create a new out of office entry
Update Out Of Office Entry
Update an existing out of office entry
Delete Out Of Office Entry
Delete an out of office entry

Webhooks

Create Webhook
Create a new webhook
List Webhooks
Get all webhooks for the authenticated user
Get Webhook
Get details of a specific webhook
Update Webhook
Update an existing webhook
Delete Webhook
Delete a webhook

Default Conferencing Apps

Get Default Conferencing App
Get the default conferencing application
Set Default Conferencing App
Set the default conferencing application

Unified Groups

List Unified Groups
List unified groups in Cal.com.
Get Unified Group
Get a unified Cal.com group by id.

Unified Organizations

List Unified Organizations
List unified organizations in Cal.com.
Get Unified Organization
Get a unified Cal.com organization by id.

Unified Roles

List Unified Roles
List unified roles in Cal.com.
Get Unified Role
Get a unified Cal.com role by id.

Unified Users

List Unified Users
List unified users in Cal.com.
Get Unified User
Get a unified Cal.com user by id.

Other (21)

Add Booking Guests
Add guests to an existing booking
Get Default Schedule
Get the default schedule for the authenticated user
Get Available Slots
Get available time slots for an event type
List Calendars
Get all connected calendars
Get Calendar OAuth URL
Get OAuth URL to connect a calendar
List Out Of Office Entries
Get all out of office entries for the authenticated user
List Conferencing Apps
Get all connected conferencing applications
Get Conferencing OAuth URL
Get OAuth URL to connect a conferencing app
Get Stripe Connect URL
Get URL to connect Stripe account
Get Unified Credentials
Get the current Cal.com connection's unified credentials and identity.
List Unified Resource Types
List unified resource types in Cal.com.
List Unified Resource Users
List unified resource users in Cal.com.
Cancel Booking
Cancel an existing booking
Reschedule Booking
Reschedule an existing booking to a new time
Confirm Booking
Confirm a pending booking
Decline Booking
Decline a pending booking request
Reserve Slot
Reserve a time slot temporarily
Check Calendar Connection
Check a calendar connection status
Disconnect Calendar
Disconnect a calendar integration
Connect Conferencing App
Connect a conferencing application
Disconnect Conferencing App
Disconnect a conferencing application

Set Up Your Cal.com MCP Server in Minutes

One endpoint. Any framework. Your agent is talking to Cal.com in under 10 lines of code.

MCP Clients

Agent Frameworks

Claude Desktop-

JSON

Claude Desktop Docs

{
  "mcpServers": {
    "stackone": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "https://api.stackone.com/mcp?x-account-id=<account_id>",
        "--header",
        "Authorization: Basic <YOUR_BASE64_TOKEN>"
      ]
    }
  }
}

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49+ actions

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All Calendar & Scheduling MCP Servers →

Platform Resources

MCP Code Mode: Keeping Tool Responses Out of Agent Context

Anthropic's code_execution processes data already in context. Custom MCP code mode keeps raw tool responses in a sandbox. 14K tokens vs 500.

11 min

Comparing BM25, TF-IDF, and Hybrid Search for MCP Tool Discovery

Benchmarking BM25, TF-IDF, and hybrid search for MCP tool discovery across 916 tools. The 80/20 TF-IDF/BM25 hybrid hits 21% Top-1 accuracy in under 1ms.

10 min

Indirect Prompt Injection Defense for MCP Tools: A Technical Guide

MCP tools that read emails, CRM records, and tickets are indirect prompt injection vectors. Here's how we built a two-tier defense that scans tool results in ~11ms.

12 min

MCP vs A2A: Architecture, Security, and When to Use Each

MCP vs A2A: what each protocol standardizes, how they differ, their shared security risks including indirect prompt injection, and when to use one, both, or a hybrid architecture.

12 min

MCP vs API: What 200+ Connector Builds Taught Us

MCP wraps APIs, it doesn't replace them. After building 200+ connectors that serve both, here's when each approach wins.

14 min read

Cal.com MCP Server FAQ

Does StackOne have a Cal.com MCP server?

Yes. StackOne offers a hosted Cal.com MCP server with 63 pre-built actions, and every action is tested and QA'd by StackOne. Connect it to Claude, Cursor, and any other MCP client, or to any agent framework through the AI Action SDK. It ships with managed agent authentication, prompt injection defense, and tool discovery with server-side execution that preserve your agent's context window and keep reasoning performance.

Cal.com MCP server vs direct API integration — what's the difference?

A Cal.com MCP server and direct API integration serve different use cases. Direct API integration is for software-to-software — backend code calling Cal.com. A Cal.com MCP server is for AI agents — MCP clients like Claude and Cursor, plus framework agents built with OpenAI, LangChain, or Vercel AI — discovering and calling Cal.com at runtime. StackOne provides both.

How does Cal.com authentication work for AI agents?

Cal.com authentication for AI agents works through a StackOne Connect Session. Create one via the dashboard or the SDK — you get an auth link and ready-to-paste config for Claude Desktop, Cursor, and other MCP clients. Your user authenticates their own Cal.com account; StackOne handles token exchange, storage, and refresh. Credentials never reach the LLM, and each user is isolated via origin_owner_id.

Are Cal.com MCP tools vulnerable to prompt injection?

Yes — Cal.com MCP tools can be vulnerable to indirect prompt injection. Any tool that reads user-written content — documents, messages, tickets, records, or free-text fields — is a potential vector. StackOne Defender scans every tool response before it enters the agent's context — regex patterns in ~1ms, then a MiniLM classifier in ~4ms. 88.7% accuracy, CPU-only.

What is the context bloat of a Cal.com agent and how do I avoid it?

Context bloat happens when Cal.com tool schemas and API responses eat your Cal.com agent's memory, preventing it from reasoning effectively. A single Cal.com query can return a massive JSON response, and connecting multiple tools compounds the problem. Tools Discovery and Code Mode reduce context bloat — loading only relevant tools per query and keeping raw responses out of the agent's context.

Can I limit which actions my Cal.com agent can access?

Yes — you can limit which actions your Cal.com agent can access directly from the StackOne dashboard. Toggle actions on or off, or restrict them to specific accounts, with no code changes to your agent. Session tokens can be scoped to exact actions so if one leaks, exposure stays contained.

Can I create custom agent actions for my Cal.com MCP server?

Yes — you can create custom agent actions for your Cal.com MCP server using Connector Builder. It's an integration agent your coding assistant (Claude Code, Cursor, or Copilot) can invoke to research Cal.com's API, generate production-ready connector YAML, test against the live API, and validate before you ship.

When should I NOT use a Cal.com MCP server?

Skip a Cal.com MCP server if your integration is purely software-to-software — direct Cal.com API integration is simpler when no AI agent is involved. For deterministic, compliance-critical operations (financial transactions, regulatory reporting), direct API gives you predictable behavior without agent-driven decision-making. MCP shines when AI agents need to dynamically discover and call Cal.com actions at runtime.

What AI frameworks and AI clients does the StackOne Cal.com MCP server support?

The StackOne Cal.com MCP server supports both. MCP clients (paste-and-go apps): Claude Desktop, Claude Code, Cursor, VS Code, Goose. Agent frameworks (code SDKs you build with): OpenAI Agents SDK, Anthropic, Vercel AI, Google ADK, CrewAI, Pydantic AI, LangChain, LangGraph, Azure AI Foundry.

Put your AI agents to work

All the tools you need to build and scale AI agent integrations, with best-in-class connectivity, execution, and security.

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Cal.com MCP Serverfor AI Agents