MCP CLI

MCP CLI client in Rust — Cross-platform MCP server interaction without runtime dependencies

A CLI for discovering, inspecting, and executing tools from Model Context Protocol (MCP) servers with lazy background daemon. Works on Linux, macOS, and Windows (via named pipes).

Vibe-kit Disclaimer

This is just an experiment for its own sake. I don't intend to rely on it heavily. Use the original https://github.com/philschmid/mcp-cli.

Quick Start

# Install from source
git clone https://github.com/gtrak/mcp-cli-rs.git
cd mcp-cli-rs
cargo build --release

# Create config at ~/.config/mcp/mcp_servers.toml
cat > ~/.config/mcp/mcp_servers.toml << 'EOF'
[[servers]]
name = "filesystem"
transport = { type = "stdio", command = "npx", args = ["-y", "@modelcontextprotocol/server-filesystem", "/home/user"] }
EOF

# List available tools
./target/release/mcp list

Why This Rewrite?

This is a Rust rewrite of the original Bun-based MCP CLI. Key improvements:

Windows Support — Full Windows compatibility using named pipes (original had Windows process spawning issues)
No Runtime Dependencies — Single compiled binary, no Bun/Node.js required
Cross-Platform — Native Unix sockets on Linux/macOS, named pipes on Windows
Better Performance — Rust's async runtime with connection caching via daemon

Installation

Prerequisites

Rust toolchain (1.70+)

From Source

# Clone and build
git clone https://github.com/gtrak/mcp-cli-rs.git
cd mcp-cli-rs
cargo build --release

# Binary will be at ./target/release/mcp
# Optional: Copy to your PATH
cp ./target/release/mcp ~/.local/bin/

Platform Notes

Linux/macOS: Uses Unix domain sockets for daemon IPC
Windows: Uses named pipes for daemon IPC (requires daemon mode for server connections)

Usage

Command Format

Two styles supported for tool calls:

# Space-separated (clearer for complex arguments)
mcp call filesystem read_file '{"path": "/etc/hosts"}'

# Slash-separated (compact)
mcp call filesystem/read_file '{"path": "/etc/hosts"}'

Basic Examples

# List all servers and their tools
mcp list
mcp list -d              # With descriptions
mcp list --json          # JSON output for scripting

# Show server information
mcp info filesystem      # Server details
mcp info filesystem read_file   # Tool schema

# Search for tools
mcp search "*file*"      # Pattern matching across all servers

# Call a tool
mcp call filesystem read_file '{"path": "/etc/hosts"}'
mcp call filesystem/read_file < /tmp/args.json   # From stdin

# Daemon control
mcp daemon               # Start daemon
mcp shutdown             # Stop daemon

Global Flags

-c, --config <PATH>      Custom config file path
    --json               Output as JSON
    --no-daemon          Run in direct mode (no connection caching)
    --auto-daemon        Auto-spawn daemon if not running (default)
    --require-daemon     Fail if daemon is not running
-h, --help               Show help
-V, --version            Show version

Configuration

Config file location (in order of precedence):

Path specified with --config
~/.config/mcp/mcp_servers.toml
~/.config/mcp/mcp.toml

TOML Format

[[servers]]
name = "filesystem"
transport = { type = "stdio", command = "npx", args = ["-y", "@modelcontextprotocol/server-filesystem", "/home/user"] }

[[servers]]
name = "fetch"
transport = { type = "stdio", command = "npx", args = ["-y", "@modelcontextprotocol/server-fetch"] }

[[servers]]
name = "http-server"
transport = { type = "http", url = "http://localhost:3000/mcp" }

# Optional: Global settings
concurrency_limit = 5    # Max concurrent operations
retry_max = 3           # Max retry attempts
retry_delay_ms = 1000   # Initial retry delay
 timeout_secs = 1800     # Operation timeout
daemon_ttl = 60         # Daemon idle timeout in seconds

Tool Filtering

[[servers]]
name = "filesystem"
transport = { type = "stdio", command = "npx", args = ["-y", "@modelcontextprotocol/server-filesystem", "/"] }

# Allow only specific tools
allowed_tools = ["read_file", "list_directory"]

# Or block specific tools
disabled_tools = ["write_file", "delete_file"]

Environment Variables

Variable	Description
`MCP_NO_DAEMON=1`	Disable daemon (direct mode)
`MCP_DAEMON_TTL=N`	Set daemon idle timeout in seconds (default: 60)

Commands

`list` — List servers and tools

mcp list                 # List all servers with tool counts
mcp list -d              # Include tool descriptions
mcp list -v              # Verbose with full schemas
mcp list --json          # Machine-readable JSON output

`info` — Show server or tool details

mcp info <server>              # Server details (transport, tools count)
mcp info <server> <tool>       # Tool schema (parameters, description)

# Examples
mcp info filesystem
mcp info filesystem read_file
mcp info fetch fetch_url

`call` — Execute a tool

# With JSON argument
mcp call <server> <tool> '<json>'
mcp call <server/tool> '<json>'

# Examples
mcp call filesystem read_file '{"path": "/etc/hosts"}'
mcp call filesystem/read_file '{"path": "/etc/hosts"}'

# With arguments from stdin
echo '{"url": "https://example.com"}' | mcp call fetch fetch_url

# Flag-style arguments (auto-converted to JSON)
mcp call fetch fetch_url --url https://example.com
mcp call filesystem read_file --path /etc/hosts --limit 100

`search` — Find tools by pattern

mcp search "*file*"      # Find tools with "file" in the name
mcp search "read*"       # Glob pattern matching

`daemon` — Connection caching

mcp daemon               # Start daemon (runs in foreground)
mcp daemon --ttl 300     # Start with custom 5-minute TTL

mcp shutdown             # Stop running daemon

Daemon modes:

--no-daemon: Direct mode, no caching (slower but simpler)
--auto-daemon: Spawn daemon if needed (default, recommended)
--require-daemon: Fail if daemon not running

Development

Setup

git clone https://github.com/gary/mcp-cli-rs.git
cd mcp-cli-rs

Build

cargo build              # Debug build
cargo build --release    # Optimized release build

Test

# Run library tests
cargo test --lib

# Run integration tests
cargo test --test '*'

# Run all tests
cargo test

Project Structure

src/
├── cli/              # CLI parsing and command dispatch
├── client/           # MCP client implementations (stdio, HTTP)
├── config/           # Configuration loading and types
├── daemon/           # Daemon lifecycle and management
├── error/            # Error types and handling
├── format/           # Output formatting (text, JSON)
├── ipc/              # Inter-process communication (sockets/pipes)
├── server/           # MCP server protocol handling
├── shutdown/         # Graceful shutdown handling
└── transport/        # Transport abstractions

Troubleshooting

"Daemon not running"

Start the daemon:

mcp daemon
# Or use direct mode:
mcp --no-daemon list

"Config file not found"

Create the config file:

mkdir -p ~/.config/mcp
cat > ~/.config/mcp/mcp_servers.toml << 'EOF'
[[servers]]
name = "filesystem"
transport = { type = "stdio", command = "npx", args = ["-y", "@modelcontextprotocol/server-filesystem", "/"] }
EOF

"Tool not found"

Check server name: mcp list
Check tool name: mcp info <server>
Verify server is running: mcp info <server>

"Connection refused" or "No such file or directory"

Verify the MCP server package is installed (e.g., npx @modelcontextprotocol/server-filesystem)
Check the command path in your config
For HTTP servers, verify the URL is accessible: curl http://localhost:3000/mcp

Windows-specific

On Windows, named pipes require the daemon to be running:

# Start daemon first
mcp daemon

# Then use in another terminal
mcp list

Getting Debug Output

# Enable debug logging
RUST_LOG=debug mcp list

# Check daemon logs
cat ~/.cache/mcp-cli/daemon.log

License

MIT License - See LICENSE for details.

Name		Name	Last commit message	Last commit date
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.github/workflows		.github/workflows
.opencode		.opencode
.planning		.planning
docs		docs
src		src
tests		tests
.gitignore		.gitignore
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
README.md		README.md

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MCP CLI

Quick Start

Why This Rewrite?

Installation

Prerequisites

From Source

Platform Notes

Usage

Command Format

Basic Examples

Global Flags

Configuration

TOML Format

Tool Filtering

Environment Variables

Commands

list — List servers and tools

info — Show server or tool details

call — Execute a tool

search — Find tools by pattern

daemon — Connection caching

Development

Setup

Build

Test

Project Structure

Troubleshooting

"Daemon not running"

"Config file not found"

"Tool not found"

"Connection refused" or "No such file or directory"

Windows-specific

Getting Debug Output

License

See Also

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`list` — List servers and tools

`info` — Show server or tool details

`call` — Execute a tool

`search` — Find tools by pattern

`daemon` — Connection caching

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