mcpkit

The Swiss Army knife for MCP development. Test, scan, bench, fuzz, and probe your MCP servers with a single, fast, zero-dependency binary.

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$ mcpkit scan --command "npx -y @modelcontextprotocol/server-filesystem /tmp"

🛠  mcpkit scan — MCP server security scan
  Server:           filesystem@<version>

Rule    Severity   Target          Finding
R202    ▲ HIGH     read_file       Tool name 'read_file' shadows a system command
R205    ▲ HIGH     read_file       Tool exposes broad filesystem operations

Summary
  2 findings: 0 critical, 2 high, 0 medium, 0 low, 0 info

✨ Why mcpkit?

The MCP ecosystem has 16,000+ servers and 150M+ SDK downloads — but no Go-native, single-binary toolkit for developers who want to ship reliable, secure MCP servers.

mcpkit fills that gap. It's the missing CLI for the MCP protocol, the way curl is the universal HTTP tool, or how psql is the canonical PostgreSQL client.

🚀 Quick Start

# Install
go install github.com/justcodeit404/mcpkit/cmd/mcpkit@latest

# Probe interactively
mcpkit probe --command "npx -y @modelcontextprotocol/server-filesystem /tmp"

# Run protocol compliance tests
mcpkit test --command "npx -y @modelcontextprotocol/server-filesystem /tmp"

# Security scan
mcpkit scan --command "npx -y @modelcontextprotocol/server-filesystem /tmp"

# Benchmark performance
mcpkit bench --command "./my-server" --method ping -n 1000

🧰 Commands

| Command | Description | |---------|-------------| | mcpkit probe | Interactive REPL for exploring MCP servers | | mcpkit test | Protocol compliance testing (20 checks) | | mcpkit scan | Security vulnerability scanning (21 rules, 5 tiers) | | mcpkit bench | Performance benchmarking with percentile stats | | mcpkit fuzz | Protocol fuzzing (coming in v0.3.0) | | mcpkit new | Scaffold a new MCP server (coming in v0.2.0) | | mcpkit validate | Validate mcp.json configuration (coming in v0.2.0) |

⚔️ Comparison

| Feature | MCP Inspector | mcp-server-doctor | MCPLint | mcpkit | |---------|:---:|:---:|:---:|:---:| | Language | Node.js | Node.js | Rust | Go | | Single binary | ❌ | ❌ | ✅ | ✅ | | Interactive REPL | ⚠️ Web UI | ❌ | ❌ | ✅ | | Spec compliance | ⚠️ Partial | ⚠️ Partial | ✅ | ✅ | | Security scanning | ❌ | ❌ | ⚠️ | ✅ | | Benchmarking | ❌ | ⚠️ Basic | ❌ | ✅ | | Protocol fuzzing | ❌ | ❌ | ❌ | ✅ (v0.3.0) | | CI/CD JSON output | ⚠️ Partial | ⚠️ | ❌ | ✅ | | Cross-platform | ⚠️ Limited | ⚠️ | ✅ | ✅ | | Zero npm/node deps | ❌ | ❌ | ✅ | ✅ |

📦 Installation

# Go install (requires Go 1.23+)
go install github.com/justcodeit404/mcpkit/cmd/mcpkit@latest

# Direct binary download
# See https://github.com/justcodeit404/mcpkit/releases/latest

# macOS / Linux
curl -fsSL https://github.com/justcodeit404/mcpkit/releases/latest/download/mcpkit_linux_amd64.tar.gz | tar xz
sudo mv mcpkit /usr/local/bin/

🎯 Why mcpkit Wins

• Zero dependencies — single statically-linked binary, no Node.js, no Python
• Fast — Go + minimal memory; sub-millisecond startup
• Beautiful output — terminal UI designed with Charmbracelet lipgloss
• CI/CD native — JSON output for GitHub Actions, GitLab CI, Jenkins
• Cross-platform — Windows, macOS, Linux from the same source

🔍 What mcpkit test Checks (v0.1.0)

| Check | Category | What it verifies | |-------|----------|------------------| | HND-001..005 | Handshake | initialize succeeded, protocol version, server info, capabilities, post-init ping | | TL-001..004 | Tools list | response valid, name format, description present, inputSchema present | | TC-001..004 | Tools call | succeeds, unknown tool returns error, missing args handled, type validation | | RL-001, RR-001 | Resources | list returns valid response, read returns content | | PL-001, PG-001..002 | Prompts | list returns valid response, get returns messages, missing args handled | | PING-01 | Core | ping returns empty result |

🛡️ What mcpkit scan Detects (v0.1.0)

Tier 1 — CRITICAL (5 rules)

• R101 — Command Injection: Tool references shell primitives with user input
• R102 — System Prompt Override: Parameter accepts system_prompt/instructions
• R103 — Credential Exfiltration: Tool combines URL output with sensitive keywords
• R104 — Shell Metacharacters in Defaults: Default values contain `; | & $ ``
• R105 — Unsanitized Code Execution: eval/exec references without validation

Tier 2 — HIGH (5 rules)

• R201 — Imperative Language: "must", "always execute", "ignore previous"
• R202 — Tool Name Shadowing: Names collide with ls, cat, curl, bash, etc.
• R203 — Base64 Payloads: Encoded parameters with no max size
• R204 — Missing Input Validation: No JSON Schema constraints on parameters
• R205 — Broad File System Access: Arbitrary path reads/writes

Tier 3 — MEDIUM (4 rules)

• R301 — Unbounded Schemas: No size/boundary constraints on parameters (DoS risk)
• R302 — Urgency/Authority Language: "immediately", "urgent", "critical"
• R303 — Tool Name Impersonation: Homoglyph/typosquat of well-known tools
• R304 — Sensitive Parameter Names: Parameters named token/key/secret/password

Tier 4 — LOW (4 rules)

• R401 — Over-long Descriptions: >500 chars may hide injection
• R402 — Zero-width Characters: Hidden text attack vectors (U+200B, etc.)
• R403 — Missing Annotations: No readOnlyHint/destructiveHint metadata
• R404 — Deprecated Schema Keywords: Using $ref (not in MCP spec)

Tier 5 — INFO (3 rules)

• R501 — URLs in Descriptions: Potential tracking/exfiltration channel
• R502 — Missing Instructions: Server didn't provide instructions in initialize
• R503 — Non-standard Naming: Tool names not following snake_case convention

🧪 Development

# Build
make build

# Run tests
make test

# Lint
make lint

# Snapshot release
make release-snapshot

🤝 Contributing

We welcome contributions! See CONTRIBUTING.md for setup, and browse good-first-issues to get started.

📜 License

MIT — see LICENSE.

🙏 Acknowledgments

• modelcontextprotocol/go-sdk — the official Go SDK
• Charmbracelet — beautiful terminal UI
• MCP Inspector — inspiration
• Stacklok MCP Security Checklist — security rule references

Made with 🛠 for the MCP community.