Go Module Review: modelcontextprotocol/go-sdk

[github-actions[bot]]

🐹 Go Fan Report: MCP Go SDK

Module Overview

The Model Context Protocol (MCP) Go SDK is the official Go implementation of the MCP specification, providing server and client APIs for building AI assistant integrations. Maintained collaboratively with Google, this SDK enables AI systems to interact with external tools, resources, and services through a standardized protocol.

Repository: https://github.com/modelcontextprotocol/go-sdk
Current Version: v1.1.1-0.20251212184941-875d1d30c2af (pseudo-version)
Latest Version: v1.2.0 (released 2025-12-22, 4 days ago)
Stars: ⭐ 3,499 | License: MIT | Forks: 316

Current Usage in gh-aw

Integration Scale

• Files: 14 files (4 core, 10 tests)
• MCP Tools: 7 tools registered (status, compile, logs, audit, mcp-inspect, add, update)
• Servers: 2 patterns (main MCP server + gateway aggregator)

Core Components

1. MCP Server (pkg/cli/mcp_server.go)

• Exposes gh-aw CLI commands as MCP tools
• Supports stdio and HTTP/SSE transports
• Uses mcp.AddTool() with type-safe tool definitions
• Implements proper context cancellation
• Custom slog logger integration

2. MCP Gateway (pkg/awmg/gateway.go)

• Aggregates multiple MCP servers into single endpoint
• Uses mcp.NewClient() for backend connections
• Implements mcp.NewServer() for proxy layer
• Supports StreamableHTTPHandler for web access
• Manages session lifecycle and connection pooling

3. MCP Inspector (pkg/cli/mcp_inspect_mcp.go)

• Connects to MCP servers via CommandTransport or StreamableClientTransport
• Lists available tools and resources
• Validates server connectivity

Key APIs Used

✅ mcp.NewServer() - Server creation with capabilities
✅ mcp.NewClient() - Client creation for connections
✅ mcp.AddTool() - Type-safe tool registration (7 tools)
✅ mcp.StdioTransport - Standard input/output transport
✅ mcp.StreamableHTTPHandler - HTTP/SSE server handler
✅ mcp.StreamableClientTransport - HTTP/SSE client transport
✅ mcp.CommandTransport - Subprocess communication
✅ ServerOptions.Capabilities - Capability declaration
✅ ServerOptions.Logger - Custom logging integration

Research Findings

Recent Activity

The MCP Go SDK is very actively maintained with significant recent development:

Latest Release (v1.2.0 - 2025-12-22):

• 🎯 Partial support for 2025-11-25 MCP specification
• 🔧 Major streamable transport reliability improvements
• 🆕 Simplified capability configuration API
• 🔐 Security enhancements (URL validation, session hijacking prevention)
• 🐛 Multiple bug fixes for production stability

Recent Commits (Last 10):

1. Icon theme improvements (named string types)
2. GitHub Pages documentation redirect
3. Transient error handling for streamable connections
4. OAuth content type validation fix
5. Capabilities API simplification
6. Root capabilities bug fix
7. URL scheme security validation
8. Change notification debouncing
9. CloseSSEStream API refinement
10. Code cleanup and refinements

Best Practices from Maintainers

Server Implementation:

• ✅ Always provide Name and Version in Implementation
• ✅ Configure capabilities explicitly via ServerOptions.Capabilities
• ✅ Set ListChanged: false for static feature sets (no dynamic changes)
• ✅ Integrate custom logger for debugging (slog recommended)
• ✅ Use context-aware operations for cancellation support

Tool Registration:

• ✅ Use struct types with json and jsonschema tags for inputs
• ✅ Return *mcp.CallToolResult with appropriate content types
• ✅ Handle context cancellation in tool handlers
• ✅ Validate inputs before processing
• ✅ Provide clear tool descriptions

Transport Selection:

• ✅ StdioTransport - Local CLI tools and direct integrations
• ✅ StreamableHTTPHandler - Web-based clients and remote access
• ✅ CommandTransport - Subprocess-based MCP servers
• ✅ IOTransport - Custom io.ReadCloser/WriteCloser scenarios

New Features in v1.2.0

2025-11-25 MCP Spec Support:

• 🎨 SEP-973: Icons and metadata for tools/resources
• ✅ SEP-986: Tool name validation
• 🔧 SEP-1024: Elicitation defaults for better UX
• 🌐 SEP-1036: URL mode elicitation
• 📡 SEP-1699: SSE polling support
• 📋 SEP-1330: Elicitation enum improvements

API Additions:

• Common error codes via jsonrpc.Error sentinels
• OAuth 2.0 Protected Resource Metadata support
• ClientCapabilities.RootsV2 for root capabilities
• Simplified Capabilities fields in options structs

Quality Improvements:

• Better SSE connection handling (non-strict mode relaxation)
• Skip non-message SSE events
• Improved context cancellation for streamable transports
• Transient error resilience (don't break connections)
• Windows CRLF handling
• Connection reuse optimization

Improvement Opportunities

⭐⭐⭐⭐ VERY GOOD Implementation Rating

The gh-aw project demonstrates excellent professional usage of the MCP Go SDK! The implementation is well-structured, follows best practices, and leverages advanced features like the gateway pattern and multiple transports.

🏃 Quick Wins

1. Upgrade to v1.2.0 ⚡ HIGH PRIORITY

• Current: v1.1.1-0.20251212184941-875d1d30c2af (pseudo-version)
• Latest: v1.2.0 (released 4 days ago)
• Benefits:
  • 🔐 Security fixes (URL validation, session hijacking prevention)
  • 🐛 Streamable transport stability improvements
  • 🎯 2025-11-25 MCP spec support (icons, elicitation, metadata)
  • 📚 Simplified capability configuration API
  • ⚡ Performance optimizations (connection reuse, debouncing)
• Impact: Improved stability, security, and access to new features
• Effort: Low (standard go get update + test verification)

2. Add Tool Icons 🎨

• v1.2.0 adds icon support (SEP-973) for better visual UX
• Could add emoji or icon URLs to the 7 registered tools
• Examples:
  • 📊 status - Workflow status overview
  • 🔨 compile - Build and validate workflows
  • 📜 logs - Workflow execution logs
  • 🔍 audit - Deep dive investigation
  • 🔎 mcp-inspect - Server introspection
  • ➕ add - Import workflows
  • 🔄 update - Sync workflows
• Impact: Better tool discoverability in MCP-aware UIs
• Effort: Low (add Icon field to mcp.Tool definitions)

3. Use Simplified Capability Configuration

• v1.2.0 simplifies capability declaration
• Current code manually constructs capabilities (verbose but correct)
• New API: Set once in ServerOptions.Capabilities
• Impact: Cleaner, more maintainable code
• Effort: Low (refactor existing capability setup)

4. Add Error Code Constants

• v1.2.0 exposes standardized error codes via jsonrpc.Error
• Currently using generic error returns in tool handlers
• Could use MCP-standardized error codes for better client handling
• Impact: Better error reporting and client compatibility
• Effort: Low (update error returns in tools)

✨ Feature Opportunities

1. Elicitation Defaults (SEP-1024)

• New v1.2.0 feature for providing input defaults
• Could improve UX for tools like compile and status
• Examples:
  • compile: default strict: true (most common case)
  • status: default empty pattern (all workflows)
  • logs: default recent run
• Impact: Better developer experience, fewer required inputs
• Effort: Medium (requires understanding elicitation API)

2. Resource Support

• SDK supports MCP resources (structured data exposure)
• Could expose workflow files, logs, audit reports as resources
• Enables browsing/reading without tool invocation
• Impact: More flexible integration patterns
• Effort: Medium (design resource API, implement handlers)

3. Prompt Templates

• SDK supports prompts (conversation templates)
• Could provide templates for common workflows
• Examples:
  • "Audit workflow run and summarize issues"
  • "Compile all workflows and fix errors"
  • "Review recent workflow logs"
• Impact: Guided user interactions, better UX
• Effort: Medium (design prompt templates)

4. URL Mode Elicitation (SEP-1036)

• New feature for URL-based input fields
• Useful for add and update tools (GitHub URLs)
• Impact: Better input validation and UX
• Effort: Medium (integrate elicitation API)

📐 Best Practice Alignment

Already Excellent ✅

• Connection timeout configuration (30s)
• Context cancellation in all tool handlers
• Custom slog logger integration
• Capability declaration (ListChanged: false)
• Tool schema generation (jsonschema tags)
• Comprehensive test coverage
• Multiple transport support

Minor Improvement 📝

• Capability configuration (v1.2.0 simplifies this)
• Error codes (v1.2.0 adds standardized codes)

🔧 General Improvements

1. Streamable Transport Resilience

• v1.2.0 significantly improved error handling
• Gateway's HTTP/SSE connections will benefit
• Automatic with upgrade (no code changes needed)
• Impact: More robust connections, better retry logic

2. Change Notification Debouncing

• v1.2.0 debounces server change notifications
• Not currently an issue (static tool set)
• Useful if dynamic tools are added later
• Impact: Performance for dynamic servers

3. Connection Reuse

• v1.2.0 improved connection reuse (Test Issue for Claude Commands #709)
• Gateway already manages sessions via map
• May see marginal performance improvement
• Impact: Slightly better resource utilization

Recommendations

Priority 1 (Do First - High Value, Low Effort)

1. ✅ Upgrade to v1.2.0 - Security, stability, new features
2. ✅ Add tool icons - Better UX with minimal effort
3. ✅ Update error handling - Use standardized error codes

Priority 2 (Do Soon - Good Value, Medium Effort)

4. ✅ Refactor capabilities - Use simplified v1.2.0 API
5. 🔄 Add elicitation defaults - Improved input experience
6. 🔄 Explore resource support - More flexible data access

Priority 3 (Consider - Future Enhancements)

7. 🔄 Create prompt templates - Guided workflows
8. 🔄 Add URL elicitation - Better input validation

Next Steps

Immediate Actions

1. Run go get github.com/modelcontextprotocol/[email protected]
2. Run test suite to verify compatibility
3. Add icons to existing tools (low effort, nice UX boost)
4. Review changelog for any breaking changes (none expected)

Follow-up Tasks

5. Refactor capability configuration using new API
6. Update error returns to use jsonrpc.Error codes
7. Explore elicitation features for better UX
8. Consider resource and prompt support for richer integration

Conclusion

The gh-aw project demonstrates excellent professional usage of the MCP Go SDK with:

• ✅ Well-structured server and gateway implementations
• ✅ 7 properly registered tools with type-safe definitions
• ✅ Multiple transport mechanisms (stdio, HTTP/SSE)
• ✅ Custom logger integration and context handling
• ✅ Comprehensive test coverage

The recommended upgrade to v1.2.0 will provide stability improvements, security fixes, and access to new MCP spec features like icons and elicitation. The implementation is production-ready with clear paths for enhancement.

---

References:

• MCP Go SDK Repository
• v1.2.0 Release Notes
• [MCP Specification]((redacted)
• SDK Documentation

Module summary saved to: specs/mods/go-sdk.md

AI generated by Go Fan

[pelikhan]

/plan

[github-actions[bot]]

🎉 Yo ho ho! Plan Command found the treasure and completed successfully! ⚓💰

[github-actions[bot]]

Plan Created ✅

I've created a parent tracking issue with 5 actionable sub-issues to implement the MCP Go SDK upgrade and improvements recommended in this Go Fan Report.

Parent Issue

Upgrade MCP Go SDK to v1.2.0 and implement improvements - Tracks the overall upgrade initiative

Sub-Issues Created

1. Upgrade MCP Go SDK to v1.2.0 - Update dependency to stable v1.2.0 release for security fixes and stability improvements

2. Add tool icons to MCP server tools - Implement visual icons for the 7 registered tools using v1.2.0's icon support (SEP-973)

3. Implement standardized MCP error codes - Use v1.2.0's jsonrpc.Error constants for better client compatibility

4. Refactor capability configuration using v1.2.0 simplified API - Clean up capability setup using the new simplified API

5. Add elicitation defaults for common tool inputs - Implement input defaults (SEP-1024) to improve developer experience

Next Steps

The issues are ready for assignment to GitHub Copilot agents. They follow a logical sequence from foundational upgrade to UX enhancements, with each task being independently completable.

AI generated by Plan Command for discussion #7710