feat(third_party): add Cal.com plugin

[PeerRich]

Adds a cal-com plugin that connects to Cal.com's official remote MCP server, hosted by Cal.com.

What's included

• third_party/cal-com/mcp.json: HTTP server at https://mcp.cal.com/mcp
• plugin.json, README, CHANGELOG, LICENSE, and logo (Cal.com's official mark, from the calcom GitHub organization)
• Marketplace and root README entries

Auth

OAuth 2.1 with Dynamic Client Registration and PKCE. Confirmed from the server: an unauthenticated initialize returns 401 with a WWW-Authenticate: Bearer resource_metadata="https://mcp.cal.com/.well-known/oauth-protected-resource/mcp" header, and /.well-known/oauth-authorization-server advertises a registration_endpoint and S256. There is no API key or client ID to configure.

Notes for reviewers

• The server exposes 65 tools across profile, event types, bookings, schedules, availability, calendars, teams, organizations, routing forms, and a generic API v2 catalog. It can write as well as read; the README calls this out.
• Users can restrict the registered tool set with a toolsets query parameter on the URL (documented in the README). The plugin ships the full set by default, matching the other hosted-MCP plugins here.
• I'm a Cal.com co-founder, so this is a first-party submission of our own server.

Validation

• node scripts/validate-plugins.mjs passes

Docs: https://cal.com/docs/mcp-server

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Note

Low Risk
Documentation and marketplace wiring only; no changes to core plugin runtime. Residual user risk is OAuth access to a write-capable external MCP, which matches other hosted integration plugins.

Overview
Adds a new cal-com third-party integration that wires Cursor agents to Cal.com’s hosted MCP server at https://mcp.cal.com/mcp.

The plugin ships the usual manifest (plugin.json), mcp.json HTTP connector, README (install, OAuth 2.1/PKCE, capabilities and optional toolsets URL filter), CHANGELOG, and LICENSE. Marketplace (marketplace.json) and the root README plugin table now list Cal.com alongside Calendly and other scheduling integrations.

Auth is OAuth with dynamic client registration—no API keys in the plugin bundle. Agents can read and write Cal.com data (bookings, event types, schedules, teams, etc.) as the signed-in user; behavior lives on Cal.com’s server, not in this repo.

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