OPAM MCP Server - OCaml Package Manager Integration

Overview

Create an MCP server that provides comprehensive integration with OPAM (OCaml Package Manager), enabling AI assistants to manage OCaml/ReasonML/Melange dependencies, analyze package information, and assist with OPAM-based development workflows.

Use Cases

Primary Use Cases

Dependency Management: Install, update, and remove OPAM packages with version resolution
Package Discovery: Search and explore OPAM packages with metadata analysis
Environment Management: Switch between OPAM switches and manage compiler versions
Dependency Analysis: Analyze project dependencies, conflicts, and upgrade paths
Build Integration: Support for dune + OPAM workflows in modern OCaml projects

Specific Scenarios

Melange + Relude Projects: Managing complex dependency chains for ReasonML → JS compilation
Multi-Platform Development: Managing dependencies for native, web, and mobile targets
CI/CD Integration: Validating dependencies and lock files in automated pipelines
Package Authoring: Analyzing reverse dependencies and package impact

Ideal API Structure

Tools (MCP Functions)

Package Management

// Install packages with version constraints
install_packages(packages: string[], switch?: string, dry_run?: boolean): Promise<InstallResult>

// Update packages or entire switch
update_packages(packages?: string[], switch?: string): Promise<UpdateResult>

// Remove packages with dependency cleanup
remove_packages(packages: string[], switch?: string): Promise<RemoveResult>

// Pin packages to specific versions or development repos
pin_package(package: string, version_or_url: string): Promise<PinResult>

Package Discovery & Information

// Search packages with filters
search_packages(query: string, tags?: string[], sort?: 'name'|'popularity'|'date'): Promise<PackageSearchResult[]>

// Get detailed package information
get_package_info(package: string, version?: string): Promise<PackageInfo>

// List available packages with filters
list_packages(installed_only?: boolean, switch?: string): Promise<PackageList>

// Show package dependencies and reverse dependencies
analyze_dependencies(package: string, recursive?: boolean): Promise<DependencyAnalysis>

Switch & Environment Management

// List all OPAM switches
list_switches(): Promise<Switch[]>

// Create new switch with specific compiler
create_switch(name: string, compiler?: string, packages?: string[]): Promise<SwitchResult>

// Switch to different OPAM environment
switch_to(switch_name: string): Promise<SwitchResult>

// Remove unused switches
remove_switch(switch_name: string): Promise<SwitchResult>

Project Analysis

// Analyze current project's OPAM dependencies
analyze_project(path?: string): Promise<ProjectAnalysis>

// Generate or update .opam files
generate_opam_file(path: string, template?: 'library'|'executable'|'mixed'): Promise<OpamFileResult>

// Lock dependencies for reproducible builds
lock_dependencies(path?: string): Promise<LockResult>

// Validate project configuration
validate_project(path?: string): Promise<ValidationResult>

Resources (MCP Data Sources)

Package Information

// Current switch information
opam://switch/current -> SwitchInfo

// Package database snapshot
opam://packages/installed -> InstalledPackage[]
opam://packages/available -> AvailablePackage[]

// Project dependency tree
opam://project/dependencies -> DependencyTree

// Lock file contents
opam://project/lockfile -> LockFileContents

Prompts (MCP Templates)

// Help with common OPAM workflows
"setup-melange-project" -> Guide for setting up Melange + Relude project
"resolve-dependency-conflict" -> Steps to resolve OPAM dependency conflicts  
"upgrade-project-dependencies" -> Safe upgrade path for project dependencies
"create-opam-package" -> Template for creating new OPAM package

Implementation Details

Core Technologies

Language: TypeScript (for consistency with MCP ecosystem)
OPAM Integration: Shell commands via opam CLI with JSON output parsing
File System: Read .opam files, dune-project files, lock files
Process Management: Spawn OPAM processes with proper error handling

Required OPAM Commands to Support

opam list --json                    # Package listing
opam show --json <package>          # Package details
opam search --json <query>          # Package search
opam install --json <packages>      # Installation
opam switch list --json             # Switch management  
opam switch create <name> <compiler> # Switch creation
opam lock --json                    # Dependency locking
opam pin --json <package> <source>  # Package pinning

Configuration Options

interface OpamMcpConfig {
  // Default OPAM switch to use
  default_switch?: string;
  
  // Project root for relative operations
  project_root?: string;
  
  // Whether to use OPAM's JSON output (requires opam 2.1+)
  use_json_output?: boolean;
  
  // Custom OPAM repository URLs
  custom_repositories?: { name: string; url: string }[];
  
  // Whether to automatically create switches for projects
  auto_create_switches?: boolean;
}

Error Handling Requirements

Network Issues: Graceful handling of repository update failures
Permission Issues: Clear messages for OPAM root permission problems
Version Conflicts: Detailed conflict resolution suggestions
Missing Dependencies: System dependency installation guidance
Switch Isolation: Proper error context for switch-specific operations

Example Usage Scenarios

Melange Project Setup

// AI assistant helping set up new Melange project
const result = await tools.create_switch("melange-project", "5.1.0");
await tools.install_packages(["melange", "relude", "dune"], "melange-project");
await tools.switch_to("melange-project");
await tools.generate_opam_file("./", "mixed");

Dependency Conflict Resolution

// AI helping resolve dependency conflicts
const conflicts = await tools.analyze_dependencies("reason-react");
const available = await tools.search_packages("react", ["reason", "melange"]);
const resolution = await tools.install_packages(["reason-react@0.11.0"], undefined, true);

CI/CD Validation

// Validating project in CI pipeline
const validation = await tools.validate_project("./");
const locks = await tools.lock_dependencies("./");
// Ensure reproducible builds

Testing Requirements

Unit Tests

OPAM command parsing and JSON output handling
Error condition handling (network failures, conflicts, etc.)
Switch isolation and environment management
File system operations (.opam, dune-project parsing)

Integration Tests

Real OPAM operations against test repositories
Multi-switch scenarios and compiler versions
Complex dependency resolution scenarios
Melange-specific package workflows

Mock Test Data

Sample .opam files for different project types
Mock OPAM JSON output for various commands
Dependency conflict scenarios
Different OPAM repository configurations

Documentation Requirements

User Documentation

Setup guide for different operating systems
Common workflows and examples
Integration with popular OCaml/ReasonML IDEs
Troubleshooting guide for common OPAM issues

Developer Documentation

API reference with TypeScript types
Extension points for custom OPAM workflows
Integration patterns with other MCP servers
Performance optimization guidelines

Success Criteria

Core Functionality ✅

All basic OPAM operations (install, remove, update, search)
Switch management and compiler version handling
Dependency analysis and conflict resolution
Project-level operations (.opam file generation, locking)

Advanced Features ✅

Integration with dune build system
Support for Melange/ReasonML specific workflows
Custom repository management
Performance optimization for large dependency trees

Quality Standards ✅

Comprehensive error handling and user-friendly messages
Full TypeScript type coverage
Integration test suite covering real OPAM scenarios
Documentation with examples for all major use cases

Related Resources

Implementation Priority: HIGH

This server is critical for OCaml/ReasonML/Melange development workflows and would fill a significant gap in the MCP ecosystem for functional programming languages.