MCP Server Builder
anthropics/skills
Guides the design and implementation of Model Context Protocol servers in TypeScript or Python, from tool naming and error messages to evaluation.
Work with Cal.com scheduling through the Cal.com MCP server: check availability, create, reschedule, cancel and confirm bookings, manage event types, schedules, attendees, teams and organization…
Install Calcom
$ npx skills add xai-org/plugin-marketplace --skill calcom -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install xai-org/plugin-marketplace calcom --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .claude/skills/calcom && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .claude/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcomType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add xai-org/plugin-marketplace --skill calcom -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install xai-org/plugin-marketplace calcom --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .agents/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .agents/skills/calcom && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .agents/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add xai-org/plugin-marketplace --skill calcom -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install xai-org/plugin-marketplace calcom --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .cursor/skills/calcom && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .cursor/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/xai-org/plugin-marketplace.git --path external_plugins/calcom/skills/calcom--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add xai-org/plugin-marketplace --skill calcom -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install xai-org/plugin-marketplace calcom --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .gemini/skills/calcom && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .gemini/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install xai-org/plugin-marketplace calcomInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add xai-org/plugin-marketplace --skill calcom -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .github/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .github/skills/calcom && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .github/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add xai-org/plugin-marketplace --skill calcom -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install xai-org/plugin-marketplace calcom --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/xai-org/plugin-marketplace.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/external_plugins/calcom/skills/calcom .opencode/skills/calcom && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "calcom" agent skill from https://github.com/xai-org/plugin-marketplace/tree/main/external_plugins/calcom/skills/calcom into .opencode/skills/calcom/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "calcom", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
calcom- GitHub stars
- 281
- Token cost
- ~1.1k tokens
- SKILL.md length
- 474 words
- Files
- 1
- Skills in repo
- 2
- Repo updated
- First seen
- Licence
- None found
At a glance
Work with Cal.com scheduling through the Cal.com MCP server: check availability, create, reschedule, cancel and confirm bookings, manage event types, schedules, attendees, teams and organization…
- Works in 4 steps: Resolve identity first. Call get_me once… → Check availability before booking or… → Confirm destructive actions.… → …
- A cal.com booking link
- SKILL.md covers Before you act, Choosing a tool, Not supported through this… and Building against Cal.com in code
- Calls npx; reaches api.cal.com
What it does
Calcom is an agent skill from xai-org/plugin-marketplace. Work with Cal.com scheduling through the Cal.com MCP server: check availability, create, reschedule, cancel and confirm bookings, manage event types, schedules, attendees, teams and organization memberships, and reach any Cal.com API v2 operation through the catalog tools. Use whenever "Cal.com", "cal.com", "calcom", a cal.com booking link, or the user's Cal.com calendar, bookings, event types or availability come up.
Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Agent Workflows. It works with Model Context Protocol. The repository describes itself as: Official xAI plugin marketplace.
When your agent uses it
- A cal.com booking link
- The users Cal.com calendar
- Availability come up
Example prompts
- “Cal.com”
- “cal.com”
- “calcom”
- “/calcom”
Requirements
- Node.js
Workflow steps
4 steps, taken from the first numbered list in SKILL.md.
- Resolve identity first. Call get_me once per session to learn the user's
- Check availability before booking or rescheduling. Always call
- Confirm destructive actions. cancel_booking, delete_event_type,
- Timestamps are UTC ISO 8601. Convert from the user's time zone (from get_me)
What it can do on your machine
Read from SKILL.md and the folder at commit 616838f. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
npx
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
api.cal.com
Also links to:
cal.com
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Calcom loads about 1.1k tokens when it runs. Until then it costs about 107 tokens; SKILL.md has 474 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Without a licence we can't republish the file, so here is its outline and opening line. It has 474 words (~1,127 tokens).
“Cal.com is open scheduling infrastructure. The calcom MCP server bundled with this plugin wraps the Cal.com API v2 and acts as the signed-in Cal.com user. Use it for anything about that user's calendar: what is booked, when they are free…”
- name
- calcom
Files
Just SKILL.md in external_plugins/calcom/skills/calcom of xai-org/plugin-marketplace.
Open the folder on GitHubat commit 616838f
Compare with similar skills
Calcom next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Calcom this skillxai-org/plugin-marketplace | 281 | — | ~1.1k | Automated safety check: Pass | None | |
| MCP Server Builderanthropics/skills | 180k | 64 repos | ~2.3k | Automated safety check: Pass | Apache-2.0 | |
| MCP Server BuildershareAI-lab/learn-claude-code | 78k | 5 repos | ~1.2k | Automated safety check: Pass | MIT | |
| MCP Integration for Pluginsanthropics/claude-plugins-official | 38k | 11 repos | ~3.1k | Automated safety check: Pass | Apache-2.0 | |
| Fastmcp Client CLIPrefectHQ/fastmcp | 28k | 1 repos | ~823 | Automated safety check: Pass | Apache-2.0 | |
| MemPalace Memory SearchMemPalace/mempalace | 59k | — | ~1.4k | Automated safety check: Pass | MIT |
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Questions about Calcom
What does Calcom do?
Work with Cal.com scheduling through the Cal.com MCP server: check availability, create, reschedule, cancel and confirm bookings, manage event types, schedules, attendees, teams and organization…. Calcom is an agent skill from xai-org/plugin-marketplace.com API v2 operation through the catalog tools.
When should I use Calcom?
Calcom fits situations like: A cal.com booking link; the users Cal.com calendar; availability come up.
How do I install Calcom in Claude Code?
Run `npx skills add xai-org/plugin-marketplace --skill calcom -a claude-code`. Or copy the skill folder (external_plugins/calcom/skills/calcom in xai-org/plugin-marketplace) into .claude/skills/calcom in your project. Claude Code loads it when a task matches its description.
How do I install Calcom in Codex?
Run `npx skills add xai-org/plugin-marketplace --skill calcom -a codex`. Or copy the skill folder (external_plugins/calcom/skills/calcom in xai-org/plugin-marketplace) into .agents/skills/calcom in your project. Codex loads it when a task matches its description.
Can I use Calcom in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add xai-org/plugin-marketplace --skill calcom -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/calcom, .gemini/skills/calcom, .github/skills/calcom and .opencode/skills/calcom in your project.
What does Calcom need to run?
Going by SKILL.md and its folder, Calcom needs the command-line tools its instructions call (npx). Our summary lists: Node.js.
Does Calcom access the network?
SKILL.md names 2 domains. In commands or code: api.cal.com; the agent is likely to contact it when it follows the instructions. As links in the text: cal.com. This is read from the text; nothing was executed.
Is Calcom safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Calcom use?
No licence was found for Calcom or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.
How many tokens does Calcom use?
About 1.1k tokens (SKILL.md is roughly 4.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Calcom?
Skills that share tags, products or a category with Calcom: MCP Server Builder (anthropics/skills, 180k stars), MCP Server Builder (shareAI-lab/learn-claude-code, 78k stars), MCP Integration for Plugins (anthropics/claude-plugins-official, 38k stars) and Fastmcp Client CLI (PrefectHQ/fastmcp, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Calcom?
xai-org (a GitHub organization) maintains it in xai-org/plugin-marketplace, which has 281 GitHub stars. The repository holds 2 skills in this directory. The repository was last updated on October 7, 2026.
Source: xai-org/plugin-marketplace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.