6 ms·

Show HN: I built a MCP server so Claude can play Minesweeper

123 points by tonypan 2y ago

Hi! I build an MCP server that allows clients to play Minesweeper. It turns out that Claude is not very good at it (makes obvious mistakes, hasn't won a single game on a 9x9 board after many attempts). I am curious how I can prompt Claude to do better?

stared 2y ago
Key things for debugging: * What is the data format it gets? Does it unambiguously correspond to output (i.e. without mistaking rows for cols, or indexes starting at 0 or 1)? * What is the prompt? * Is the model allowed to think? (If it is just JSON response, I expect it to suck, as tokens are units of thinking.)
- viraptor 2y ago
  One way to sanity check would be to ask it to reproduce the board with the new position marked to make sure the board model works as expected.
- tonypan 2y ago
  I noticed that Claude often tries to click out of bounds even though in the prompt I tell it that the index is zero based.
_joel 2y ago
Maybe tell it it's a champion Minesweeper player and that loss is not an option :)
- lgas 2y ago
  Based on some of the recent leaked prompts I imagine something like "The mines are connected to actual bombs that will blow up your family if you make a mistake" might work best.
  - bredren 2y ago
    Realize this must be somewhat tic, but curious about a link to example leaked related prompt?
    - 111111101101 2y ago
      https://simonwillison.net/2025/Feb/25/leaked-windsurf-prompt/ https://simonwillison.net/2025/Feb/25/leaked-windsurf-prompt...
breckenedge 2y ago
Yea Claude sucks at minesweeper (and many spatial reasoning tasks), but isn’t an idea of MCPs is that Claude should be able to ask an MCP what the next best move is rather than figuring it out itself? Like offload hard thinking/reasoning to purpose-built solvers because they are deterministic? Though I guess you’d expect a reasoning model to be able to come up with its own solvers on the fly, especially for well-known problems. Maybe having access to an MCP itself is confusing it?
- fragmede 2y ago
  MCP generically connects Claude to an environment, so it can be used to connect Claude to minesweeper, and then also to connect it to a CSP solver. Or a calculator and a dictionary. Or your GitHub and a devbox. Or Unity and a 3d printer.
  - breckenedge 2y ago
    Curious, I’ve yet to see Claude effectively use Unity.
    - fragmede 2y ago
      That repo's only a week old, give it some time. Did Mario not do it for you? https://youtu.be/dCC7QoV5a6E https://youtu.be/dCC7QoV5a6E
      - breckenedge 2y ago
        2 days old :D where are people seeing these releases announced? I swear we need an MCP weekly email digest
        emersonmacro 2y ago
        Pulse MCP has a weekly email digest
- dartos 2y ago
ericol 2y ago
By just looking at the README from the repo (Would look more deeply into this later) you're replying with an image of the current status? If you expect Claude to interpret the image corretly may be you're asking for too much. Besides the image (Gotta say I didn't know you could fed Claude images in MCP that's incredible cool) I'd rather / also return some json payload that informs Claude which positions has "cleared" neighbor positions, and their value. E.g.: {"loc": {"x": 4, "y": 3}, "neighbors": [{"loc": {"x": 4, "y": 4}, "value": 1}, ... ]} (Might not be valid json, just wrote that by hand on the fly) I would report only on the positions that has cleared neighbors, and hope for the best. Good luck! (Impressive work BTW, I think we haven't even started to see the possibilities of MCP and I love people being this imaginative)
- ericol 2y ago
  An interesting exercise here would be to make the MCP server show the actual state in a window and return to Claude just the json payload with the status.
  - tonypan 2y ago
    Good idea! I've updated the game server so a human can watch the game in real-time. Updated the README with a screen recording: https://github.com/tonypan2/minesweeper-mcp-server https://github.com/tonypan2/minesweeper-mcp-server
codegladiator 2y ago
Ditch the image use this format for board representation ``` { "game_state": { "board_size": { "width": 9, "height": 9 }, "mines_total": 10, "mines_flagged": 2, "game_status": "in_progress", // "in_progress", "won", "lost" "time_elapsed": 45, "difficulty": "beginner" // "beginner", "intermediate", "expert", "custom" }, "board": [ ["1", "?", "?", "2", "1", "1", "1", "1", "0"], ["1", "2", "?", "2", "?", "1", "1", "?", "0"], ["0", "1", "1", "2", "1", "1", "1", "1", "0"], ["0", "0", "0", "0", "0", "0", "0", "0", "0"], ["1", "1", "0", "0", "0", "0", "0", "0", "0"], ["?", "1", "0", "0", "0", "1", "1", "1", "0"], ["1", "1", "0", "0", "0", "1", "F", "1", "0"], ["0", "0", "0", "0", "0", "1", "1", "1", "0"], ["0", "0", "0", "0", "0", "0", "0", "0", "0"] ], "last_action": { "action_type": "reveal", "x": 3, "y": 2, "result": "revealed_number", "timestamp": 1710931245 } } ``` and this format for llm response generation ``` { "action": { "action_type": "reveal", // "reveal", "flag", "unflag", "chord" "x": 5, "y": 3, "confidence": 0.95, "reasoning": "This cell is surrounded by revealed cells with low numbers, making it a safe choice." }, "game_analysis": { "identified_safe_cells": [[5, 3], [2, 5]], "identified_mine_cells": [[6, 1], [8, 2]], "uncertain_cells": [[1, 1], [2, 2]], "strategy": "Targeting isolated revealed areas first to gain more information." } } ``` It should fix all your issues plus also make it cheaper to play
lopsidedgrin 2y ago
Teach Claude how to play Solitaire or Candy Crush at work and we will have come full circle.
rcarmo 2y ago
MCP is the new agentic, it seems. Most MCP stuff I've seen seems over-engineered, but this one was actually fun to check out.
jakeprins 2y ago
cool
helsinki 2y ago
Maybe I’m misunderstanding, but how is the actual game board / UI being rendered? I only see a MCP protocol definition.
- tonypan 2y ago
  The game server is another Node app I built: https://github.com/tonypan2/minesweeper-server https://github.com/tonypan2/minesweeper-server.
punkpeye 2y ago
Awesome to see MCP related work surfacing on the front page of HN!
tmitchel2 2y ago
It feels nuts to me that there is a push away from strict APIs to conversational interfaces for products and then the actual technology itself under the hood is translating that into a strict set of API calls in order to understand something. Would it not be better to seek interoperability with fairly well scripted natural language handshake. I feel like MCP is built for understanding language and Syntax to a greater degree but not random tools and APIs.
cbm-vic-20 2y ago
For the acroym-averse: MCP = Model Context Protocol https://modelcontextprotocol.io/ https://modelcontextprotocol.io/ "MCP is an open protocol that standardizes how applications provide context to LLMs."
- speed_spread 2y ago
  Such hubris in naming. Connaisseurs know that MCP is forever reserved to Tron's Master Control Program.
xunil2ycom 2y ago
Why
minhoryang 2y ago
Why don't you play Go instead of Minesweeper?
kristianp 2y ago
How about chess? https://github.com/alexandreroman/mcp-chess https://github.com/alexandreroman/mcp-chess
road42runner 2y ago
nice
paugay 2y ago
Can you please share the original prompt you are using?

123 points by tonypan 2y ago

stared 2y ago

Key things for debugging: * What is the data format it gets? Does it unambiguously correspond to output (i.e. without mistaking rows for cols, or indexes starting at 0 or 1)? * What is the prompt? * Is the model allowed to think? (If it is just JSON response, I expect it to suck, as tokens are units of thinking.)

viraptor 2y ago
One way to sanity check would be to ask it to reproduce the board with the new position marked to make sure the board model works as expected.
tonypan 2y ago
I noticed that Claude often tries to click out of bounds even though in the prompt I tell it that the index is zero based.

_joel 2y ago

Maybe tell it it's a champion Minesweeper player and that loss is not an option :)

lgas 2y ago
Based on some of the recent leaked prompts I imagine something like "The mines are connected to actual bombs that will blow up your family if you make a mistake" might work best.
- bredren 2y ago
  Realize this must be somewhat tic, but curious about a link to example leaked related prompt?
  - 111111101101 2y ago
    https://simonwillison.net/2025/Feb/25/leaked-windsurf-prompt/ https://simonwillison.net/2025/Feb/25/leaked-windsurf-prompt...

breckenedge 2y ago

Yea Claude sucks at minesweeper (and many spatial reasoning tasks), but isn’t an idea of MCPs is that Claude should be able to ask an MCP what the next best move is rather than figuring it out itself? Like offload hard thinking/reasoning to purpose-built solvers because they are deterministic? Though I guess you’d expect a reasoning model to be able to come up with its own solvers on the fly, especially for well-known problems. Maybe having access to an MCP itself is confusing it?

fragmede 2y ago
MCP generically connects Claude to an environment, so it can be used to connect Claude to minesweeper, and then also to connect it to a CSP solver. Or a calculator and a dictionary. Or your GitHub and a devbox. Or Unity and a 3d printer.
- breckenedge 2y ago
  Curious, I’ve yet to see Claude effectively use Unity.
  - fragmede 2y ago
    That repo's only a week old, give it some time. Did Mario not do it for you? https://youtu.be/dCC7QoV5a6E https://youtu.be/dCC7QoV5a6E
    - breckenedge 2y ago
      2 days old :D where are people seeing these releases announced? I swear we need an MCP weekly email digest
      - emersonmacro 2y ago
        Pulse MCP has a weekly email digest
dartos 2y ago

ericol 2y ago

By just looking at the README from the repo (Would look more deeply into this later) you're replying with an image of the current status? If you expect Claude to interpret the image corretly may be you're asking for too much. Besides the image (Gotta say I didn't know you could fed Claude images in MCP that's incredible cool) I'd rather / also return some json payload that informs Claude which positions has "cleared" neighbor positions, and their value. E.g.: {"loc": {"x": 4, "y": 3}, "neighbors": [{"loc": {"x": 4, "y": 4}, "value": 1}, ... ]} (Might not be valid json, just wrote that by hand on the fly) I would report only on the positions that has cleared neighbors, and hope for the best. Good luck! (Impressive work BTW, I think we haven't even started to see the possibilities of MCP and I love people being this imaginative)

ericol 2y ago
An interesting exercise here would be to make the MCP server show the actual state in a window and return to Claude just the json payload with the status.
- tonypan 2y ago
  Good idea! I've updated the game server so a human can watch the game in real-time. Updated the README with a screen recording: https://github.com/tonypan2/minesweeper-mcp-server https://github.com/tonypan2/minesweeper-mcp-server

codegladiator 2y ago

Ditch the image use this format for board representation ``` { "game_state": { "board_size": { "width": 9, "height": 9 }, "mines_total": 10, "mines_flagged": 2, "game_status": "in_progress", // "in_progress", "won", "lost" "time_elapsed": 45, "difficulty": "beginner" // "beginner", "intermediate", "expert", "custom" }, "board": [ ["1", "?", "?", "2", "1", "1", "1", "1", "0"], ["1", "2", "?", "2", "?", "1", "1", "?", "0"], ["0", "1", "1", "2", "1", "1", "1", "1", "0"], ["0", "0", "0", "0", "0", "0", "0", "0", "0"], ["1", "1", "0", "0", "0", "0", "0", "0", "0"], ["?", "1", "0", "0", "0", "1", "1", "1", "0"], ["1", "1", "0", "0", "0", "1", "F", "1", "0"], ["0", "0", "0", "0", "0", "1", "1", "1", "0"], ["0", "0", "0", "0", "0", "0", "0", "0", "0"] ], "last_action": { "action_type": "reveal", "x": 3, "y": 2, "result": "revealed_number", "timestamp": 1710931245 } } ``` and this format for llm response generation ``` { "action": { "action_type": "reveal", // "reveal", "flag", "unflag", "chord" "x": 5, "y": 3, "confidence": 0.95, "reasoning": "This cell is surrounded by revealed cells with low numbers, making it a safe choice." }, "game_analysis": { "identified_safe_cells": [[5, 3], [2, 5]], "identified_mine_cells": [[6, 1], [8, 2]], "uncertain_cells": [[1, 1], [2, 2]], "strategy": "Targeting isolated revealed areas first to gain more information." } } ``` It should fix all your issues plus also make it cheaper to play

lopsidedgrin 2y ago

Teach Claude how to play Solitaire or Candy Crush at work and we will have come full circle.

rcarmo 2y ago

MCP is the new agentic, it seems. Most MCP stuff I've seen seems over-engineered, but this one was actually fun to check out.

jakeprins 2y ago

cool

helsinki 2y ago

Maybe I’m misunderstanding, but how is the actual game board / UI being rendered? I only see a MCP protocol definition.

tonypan 2y ago
The game server is another Node app I built: https://github.com/tonypan2/minesweeper-server https://github.com/tonypan2/minesweeper-server.

punkpeye 2y ago

Awesome to see MCP related work surfacing on the front page of HN!

tmitchel2 2y ago

It feels nuts to me that there is a push away from strict APIs to conversational interfaces for products and then the actual technology itself under the hood is translating that into a strict set of API calls in order to understand something. Would it not be better to seek interoperability with fairly well scripted natural language handshake. I feel like MCP is built for understanding language and Syntax to a greater degree but not random tools and APIs.

cbm-vic-20 2y ago

For the acroym-averse: MCP = Model Context Protocol https://modelcontextprotocol.io/ https://modelcontextprotocol.io/ "MCP is an open protocol that standardizes how applications provide context to LLMs."

speed_spread 2y ago
Such hubris in naming. Connaisseurs know that MCP is forever reserved to Tron's Master Control Program.

xunil2ycom 2y ago

Why

minhoryang 2y ago

Why don't you play Go instead of Minesweeper?

kristianp 2y ago

How about chess? https://github.com/alexandreroman/mcp-chess https://github.com/alexandreroman/mcp-chess

road42runner 2y ago

nice

paugay 2y ago

Can you please share the original prompt you are using?