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.
Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool.
Install Horizon Cast
$ npx skills add peters/horizon --skill horizon-cast -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install peters/horizon horizon-cast --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/peters/horizon.git skills-src && mkdir -p .claude/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .claude/skills/horizon-cast && 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 "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .claude/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-castType 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 peters/horizon --skill horizon-cast -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install peters/horizon horizon-cast --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/peters/horizon.git skills-src && mkdir -p .agents/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .agents/skills/horizon-cast && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .agents/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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 peters/horizon --skill horizon-cast -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install peters/horizon horizon-cast --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/peters/horizon.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .cursor/skills/horizon-cast && 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 "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .cursor/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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/peters/horizon.git --path assets/plugins/codex/skills/horizon-cast--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 peters/horizon --skill horizon-cast -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install peters/horizon horizon-cast --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/peters/horizon.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .gemini/skills/horizon-cast && 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 "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .gemini/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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 peters/horizon horizon-castInstalls 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 peters/horizon --skill horizon-cast -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/peters/horizon.git skills-src && mkdir -p .github/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .github/skills/horizon-cast && 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 "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .github/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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 peters/horizon --skill horizon-cast -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install peters/horizon horizon-cast --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/peters/horizon.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/assets/plugins/codex/skills/horizon-cast .opencode/skills/horizon-cast && 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 "horizon-cast" agent skill from https://github.com/peters/horizon/tree/main/assets/plugins/codex/skills/horizon-cast into .opencode/skills/horizon-cast/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "horizon-cast", 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
horizon-cast- GitHub stars
- 716
- Token cost
- ~227 tokens
- SKILL.md length
- 106 words
- Files
- 2 (incl. references)
- Skills in repo
- 6
- Repo updated
- First seen
- Licence
- MIT
At a glance
Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool.
- Receiver discovery
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Tasks that involve MCP servers
What it does
Horizon Cast is an agent skill from peters/horizon. Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool. Use for receiver discovery, pairing, casting status, and stopping casts.
Its SKILL.md is about 230 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/casting.md`).
It sits in Agent Workflows, covering MCP servers. It works with Model Context Protocol. The repository describes itself as: GPU-accelerated terminal board that puts all your sessions on an infinite canvas. The licence is MIT.
When your agent uses it
- Receiver discovery
- Tasks that involve MCP servers
Example prompts
- “/horizon-cast”
What it can do on your machine
Read from SKILL.md and the folder at commit e2e6058. 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
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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
Horizon Cast loads about 227 tokens when it runs, and up to ~773 if it reads all its reference files. Until then it costs about 49 tokens; SKILL.md has 106 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
The full file from peters/horizon at commit e2e6058, republished under its MIT licence (© peters). 106 words, ~227 tokens.
Download SKILL.mdSave it as
.claude/skills/horizon-cast/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.- name
- horizon-cast
- description
- Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool. Use for receiver discovery, pairing, casting status, and stopping casts.
Horizon casting
Use the public cast tool on the Horizon browser MCP server (--browser-mcp).
The calling agent must run in a Horizon workspace on Linux.
Read the casting reference before receiver or session operations.
Use the current tool schema for arguments. If the tool or supporting host is absent,
report the missing capability. Do not use private runtime files or another capture path.
A task to examine casting does not authorize a cast to a real TV. Start, pair, stop, or forget only within the user's requested receiver and task. Application capture needs the person's permission in the Cast picker. An agent cannot grant that permission.
© peters, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 1 other file (references) in assets/plugins/codex/skills/horizon-cast of peters/horizon.
- SKILL.md
- references/casting.md
Open the folder on GitHubat commit e2e6058
Compare with similar skills
Horizon Cast 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 |
|---|---|---|---|---|---|---|
| Horizon Cast this skillpeters/horizon | 716 | — | ~227 | Automated safety check: Pass | MIT | |
| MCP Server Builderanthropics/skills | 180k | 63 repos | ~2.3k | Automated safety check: Pass | Apache-2.0 | |
| MCP Server BuildershareAI-lab/learn-claude-code | 78k | 4 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 | |
| Crush Configurationcharmbracelet/crush | 29k | — | ~3.7k | Automated safety check: Pass | Custom licence | |
| Context Mode Output Sandboxmksglu/context-mode | 26k | — | ~4.1k | Automated safety check: Pass | Custom licence |
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More from peters/horizon
Horizon Speech
peters/horizon
Check that a microphone is usable for Horizon dictation and report which layer is at fault — no signal, bad level, or a genuine model/accent limit.
Horizon Device
peters/horizon
Manage Horizon native VNC Device panels and drive isolated local desktops for simulators and native application tests through devicepanel and the horizon-device CLI/MCP.
Horizon App Testing
peters/horizon
Run or inspect declared iOS and Android native app tests through Horizon devicetestrun and app MCP tools.
Horizon Browser
peters/horizon
Control, inspect, or audit Horizon browser panels through public browser MCP tools.
Horizon Cloud
peters/horizon
Inspect Horizon cloud offers and companions, read or act on the cloud list of your workspace, control explicitly authorized companion workers, use a worker Local Network Bridge, or ask for GitHub…
Related
Works with
Categories
Questions about Horizon Cast
What does Horizon Cast do?
Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool. Horizon Cast is an agent skill from peters/horizon. Cast Horizon panels, workspaces, cloud cards, or its main window to Apple TV through the public cast MCP tool.
When should I use Horizon Cast?
Horizon Cast fits situations like: receiver discovery; tasks that involve MCP servers.
How do I install Horizon Cast in Claude Code?
Run `npx skills add peters/horizon --skill horizon-cast -a claude-code`. Or copy the skill folder (assets/plugins/codex/skills/horizon-cast in peters/horizon) into .claude/skills/horizon-cast in your project. Claude Code loads it when a task matches its description.
How do I install Horizon Cast in Codex?
Run `npx skills add peters/horizon --skill horizon-cast -a codex`. Or copy the skill folder (assets/plugins/codex/skills/horizon-cast in peters/horizon) into .agents/skills/horizon-cast in your project. Codex loads it when a task matches its description.
Can I use Horizon Cast 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 peters/horizon --skill horizon-cast -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/horizon-cast, .gemini/skills/horizon-cast, .github/skills/horizon-cast and .opencode/skills/horizon-cast in your project.
What does Horizon Cast need to run?
SKILL.md names no scripts, command-line tools or credentials: Horizon Cast is instructions for the agent only.
Does Horizon Cast access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Horizon Cast 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 Horizon Cast use?
Horizon Cast is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Horizon Cast use?
About 227 tokens (SKILL.md is roughly 908 characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 546 tokens, read only when the agent opens those files.
What are the alternatives to Horizon Cast?
Skills that share tags, products or a category with Horizon Cast: 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 Crush Configuration (charmbracelet/crush, 29k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Horizon Cast?
peters (a GitHub user) maintains it in peters/horizon, which has 716 GitHub stars. The repository holds 6 skills in this directory. The repository was last updated on October 11, 2026.
Source: peters/horizon on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.