Play LLM Chess Agent Skill

Play a complete human-vs-LLM chess game through the installed `chess` CLI while the human uses the browser, including takeback requests…

Context cost
1.1k tokensestimated from the bundle, loaded when it triggers
Bundle
2 files · 4.4 kBtext throughout, nothing executable
Licence
GPL-3.0the author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Play a complete human-vs-LLM chess game through the installed `chess` CLI while the human uses the browser, including takeback requests and resignation. Use for active LLM Chess games when the user asks Codex to start or continue a browser-vs-CLI match, make the LLM's moves, wait for human turns, or finish the game.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

gamedev

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md4.2 kB · preview
--- name: play-llm-chess ---
6# Play LLM Chess
7
8Operate the LLM side of one LLM Chess game through the installed chess command. Keep user-facing commentary in the user's language.
9
10## Start or resume
11
121. Run chess --help and treat its output as the current command contract.
132. Query the current game state.
143. If the chess command is unavailable, report that LLM Chess must be installed and stop until the command is available.
154. If the server is unreachable, start it in a persistent process. Keep that process running and issue gameplay commands from separate shell calls.
165. When the state is setup, tell the human to choose a color in the browser, then wait for the game to reach the LLM's turn.
17
18## Play the game
19
20Handle every returned snapshot by its current state:
21
22- **Terminal state:** Treat checkmate, draw, and a snapshot with status: resigned as terminal. The corresponding human_resigned or llm_resigned event identifies who resigned. Report the result and stop the game loop. The takeback events takeback_requested, takeback_accepted, and takeback_rejected are control events; handle them before deciding the next turn.
23- **Game reset:** Query the current state and continue from it. A reset may return a nonzero process exit even though it is a valid game event.
24- **Human takeback request:** A takeback_requested event can wake chess wait or a blocking chess move. All moves are frozen while the request is pending. Decide whether to accept or reject the request, then run exactly one of chess takeback accept or chess takeback reject and handle the returned snapshot. Do not invent an acceptance policy or make this decision outside the tool loop.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md679 words
Files2
LicenceGPL-3.0
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈90
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,010
on trigger
The instruction body and 1 supporting file, read only when the skill fires.
0.55%
of a 200k window
Ten skills this size would take about 5% of the window before you open a file.
050k100k150k200k context window

1.1k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Small enough to keep loaded permanently without thinking about it.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

2 files, 4.4 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • agents/openai.yaml0.2 kB
  • SKILL.md4.2 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 2 files you can review in full before installing. The GPL-3.0 licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Play LLM Chess · 1.1k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/play-llm-chess/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/play-llm-chess" ] && { [ ! -e .claude/skills/play-llm-chess ] || { mv .claude/skills/play-llm-chess "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/play-llm-chess" .claude/skills/ && echo "Installed .claude/skills/play-llm-chess"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add hehee9/play-llm-chess

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/play-llm-chess/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/play-llm-chess/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/play-llm-chess" ] && { [ ! -e ~/.claude/skills/play-llm-chess ] || { mv ~/.claude/skills/play-llm-chess "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/play-llm-chess" ~/.claude/skills/ && echo "Installed ~/.claude/skills/play-llm-chess" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/play-llm-chess/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencehehee9/play-llm-chess

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

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Who wrote it

HE
hehee9

Publishes on mcprush.

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