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Z3 MCP Server

A Model Context Protocol (MCP) server that provides access to the Z3 Theorem Prover and constraint solver through standardized MCP tools.

Overview

This server exposes Z3's constraint solving capabilities through MCP, allowing AI assistants and other MCP clients to solve SMT-LIB problems using the Z3 theorem prover. The server includes optional sandboxing for secure execution.

Features

• Z3 Integration: Execute Z3 constraint solver on SMT-LIB input
• Configurable Timeout: Set custom timeout values for solver operations (default: 10 seconds)
• Cross-Platform Sandboxing: Run Z3 in a sandboxed environment on macOS and Linux for enhanced security
• MCP Protocol: Standard Model Context Protocol interface for tool integration

Prerequisites

• Go 1.24.4 or later
• Z3 theorem prover installed on your system
• For sandboxing:
  • macOS: sandbox-exec command (built-in)
  • Linux: bwrap (bubblewrap) package

Installing Dependencies

Z3 Theorem Prover:

macOS (Homebrew):

brew install z3

Linux (Ubuntu/Debian):

sudo apt-get install z3

Sandboxing Dependencies:

Linux (Ubuntu/Debian):

sudo apt-get install bubblewrap

Linux (Fedora/RHEL):

sudo dnf install bubblewrap

Other platforms: See Z3's official installation guide

Installation

1. Clone the repository:

git clone <repository-url>
cd z3-mcp

2. Install dependencies:

go mod download

3. Build the server:

go build -o z3-mcp-server

Usage

Basic Usage

Start the server on stdin/stdout (standard MCP mode):

./z3-mcp-server

With Sandboxing

Enable sandboxing for enhanced security:

./z3-mcp-server -sandbox

The sandboxing implementation varies by platform:

• macOS: Uses sandbox-exec with the included z3.sb profile
• Linux: Uses bubblewrap with network isolation and read-only filesystem access

Docker

Build and run using Docker:

docker build -t z3-mcp .
docker run -i z3-mcp

Docker with Seccomp Profile

For enhanced security, run the container with the included seccomp profile:

docker run --security-opt seccomp=./seccomp-profile.json -i z3-mcp

The seccomp profile is based on Docker's official default profile with all network-related syscalls removed, providing production-grade security while maintaining full container compatibility.

MCP Tool Interface

The server provides one MCP tool:

z3

Executes the Z3 constraint solver on SMT-LIB input.

Parameters:

• input (string, required): The SMT-LIB input to solve
• timeout (number, optional): Timeout in seconds for the Z3 solver (default: 10)

Example SMT-LIB input:

(declare-const x Int)
(declare-const y Int)
(assert (> x y))
(assert (= x 10))
(check-sat)
(get-model)

Security Features

Sandboxing

When enabled with the -sandbox flag, Z3 runs within a restricted sandbox that:

• Denies network access
• Restricts file system writes
• Allows only necessary file reads
• Limits process execution to Z3 only
• Isolates process namespace (Linux)

Platform-specific implementations:

• macOS: Uses sandbox-exec with the z3.sb profile
• Linux: Uses bubblewrap with comprehensive filesystem and network isolation
• Docker: Custom seccomp profile (seccomp-profile.json) restricting system calls

License

MIT License - see file for details.