add_input
Append characters to input buffer. Use when status is WAITING_FOR_INPUT. Outputs the engine status.
LABSCO SUMMARY
A real debugger for Brainfuck, not just an interpreter.
The state is what makes it useful: after every step you can read memory, both pointers and the output so far, with a window around the pointer when the whole tape is too much. run executes to completion and an infinite loop will hang the server, so pass it the instruction limit, or step a fixed count instead.
What it is
A Node server that is a Brainfuck interpreter with its debugger exposed: load source, step or run it, feed it input, and read memory, pointers and output at any point.
What you get
- Source loaded with a configurable tape size, min/max cell values and initial input, resetting the debugger
- A chosen number of instructions executed, with a state summary after each stop
- The program run to completion or until it blocks on input, with an optional instruction limit
- Characters appended to the input buffer while the program is waiting for them
- Full state — memory, pointers, output — or just a window of cells around the pointer
- The output string produced so far, on its own
- Overflow and underflow detection, and bracket matching validated before execution
Requirements
npx — npx brainfaq-mcp starts it in stdio mode, which is all any client config needs. Licensed CC BY-SA 4.0.
Setup effort
One command — npx -y brainfaq-mcp
USE CASES
01
Finding out why a Brainfuck program prints the wrong thing
Load the source, step a few instructions at a time, and read the tape and pointers between stops.
02
Running a program that expects input
Run until it blocks, append the characters it is waiting for, and carry on.
03
Checking output without dumping the whole machine state
Read just the output string produced so far.
04
Testing a program against a smaller tape
Load the same source with a different tape size and cell value limits, and see where it overflows.
05
Getting through a long stretch without hanging
Run with an instruction limit rather than to completion, then inspect where it got to.
6 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
get_state
Get the current full state (memory, pointers, output). When windowRadius is not specified, returns the entire tape which may be a large amount of data.
load_code
Reset the debugger and load new Brainfuck source code.
read_output
Get the full output string generated so far.
run
Run the program until it finishes or waits for input. Infinite loops WILL hang the server. Then outputs the summary of the current state.
step
Execute a specific number of instructions (default 1). Then outputs the summary of the current state.
BEFORE YOU INSTALL
What to know first
Tools you get
6 tools when we connected.
Requires
npx on PATH
CONTEXT COST
Light Standing cost
Rated by the size of the 6 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"brainfaq-mcp": {
"command": "npx",
"args": [
"-y",
"brainfaq-mcp"
]
}
}
}npx
TERMINAL
npx -y brainfaq-mcp
