feat: Add title field support for human-friendly display names

[davidleitw]

Add Title Field Support for Human-Friendly Display Names

• Implement BaseMetadata interface for consistent title handling
• Add Title field to Tool, Prompt, Resource, ResourceTemplate
• Add GetDisplayName() helper with title → annotations.title → name fallback
• Add WithTitle/WithPromptTitle/WithResourceTitle/WithTemplateTitle options
• Fix Tool JSON serialization to include title field
• Add comprehensive tests and update examples
• Fully backward compatible

Resolves #418

Description

This PR implements Task #418 by adding comprehensive title field support across all MCP object types to provide human-friendly display names while maintaining programmatic identification through the existing name fields.

What We've Implemented

Core Infrastructure:

• Created BaseMetadata interface with GetName() and GetTitle() methods for consistent behavior across all types
• Added GetDisplayName() helper function that implements the fallback logic: title → annotations.title → name
• All MCP object types (Tool, Prompt, Resource, ResourceTemplate) now implement this interface

Title Field Support:

• Added Title field to all relevant structs with json:"title,omitempty" for optional serialization
• Tool supports the full fallback chain: direct title → annotations.title → name
• Other types (Prompt, Resource, ResourceTemplate) support: title → name fallback

API Enhancements:

• WithTitle() - Configure Tool title (takes precedence over annotation title)
• WithPromptTitle() - Configure Prompt title
• WithResourceTitle() - Configure Resource title
• WithTemplateTitle() - Configure ResourceTemplate title
• Fixed Tool.MarshalJSON() to properly serialize the title field

Current Behavior

// Tool with multiple title options
tool := NewTool("search-files",
    WithTitle("File Search"),  // Direct title (highest priority)
    WithTitleAnnotation("Legacy Title"), // Annotation title (fallback)
)

// GetDisplayName() returns "File Search" (direct title wins)
displayName := GetDisplayName(&tool)

// Other types with simple title support  
prompt := NewPrompt("user-prompt", WithPromptTitle("User Input Prompt"))
resource := NewResource("/api/data", "api-data", WithResourceTitle("API Data"))

Fallback Priority:

1. Tool: title → annotations.title → name
2. Others: title → name

Testing & Compatibility

• Added comprehensive test suite covering all types and fallback scenarios
• Updated all examples to demonstrate title usage
• 100% backward compatible - existing code works unchanged
• All title fields are optional and won't affect existing JSON serialization

Fixes #418

Type of Change

• New feature (non-breaking change that adds functionality)
• MCP spec compatibility implementation
• Bug fix (non-breaking change that fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring (no functional changes)
• Performance improvement
• Tests only (no functional changes)
• Other (please describe):

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• I have updated the documentation accordingly

MCP Spec Compliance

• Implementation follows the specification exactly

Additional Information

Design Decisions:

• Chose to implement BaseMetadata interface for consistency rather than individual methods per type
• Tool maintains backward compatibility with existing annotations.title while adding direct title support
• Used functional options pattern to maintain API consistency with existing codebase

Testing Coverage:

• Interface compliance tests ensure all types implement BaseMetadata
• Fallback logic tests for each type and scenario
• JSON serialization/deserialization tests for Tool (most complex case)
• All tests pass and maintain existing functionality

This implementation provides a clean foundation for human-readable display names across the MCP ecosystem. Any feedback on the design approach, additional test scenarios, or edge cases would be greatly appreciated. Thank you for taking the time to review this PR!

Summary by CodeRabbit

• New Features

  • Added support for human-friendly display titles to tools, prompts, resources, and resource templates.
  • Display titles can now be set via new options and appear in JSON output where applicable.
  • Introduced a unified method to retrieve display names across these entities.
  • Updated example tools and resources with descriptive titles for better clarity.

• Tests

  • Added tests to verify display name retrieval and JSON serialization of titles.

[coderabbitai]

Walkthrough

The changes introduce a new optional Title field to several core types (Tool, Prompt, Resource, ResourceTemplate) to support human-friendly display names. Corresponding getter methods, functional options, and a BaseMetadata interface are added. Display name precedence logic and helper utilities are implemented, alongside comprehensive tests.

Changes

Files / Grouped Files	Change Summary
mcp/types.go	Added Title field and GetTitle() to Resource and ResourceTemplate; introduced BaseMetadata interface.
mcp/prompts.go	Added Title field, GetTitle() method, and WithPromptTitle() option to Prompt.
mcp/tools.go	Added Title field, GetTitle(), WithTitle() option, and updated JSON marshaling for Tool.
mcp/resources.go	Added WithResourceTitle() and WithTemplateTitle() functional options.
mcp/utils.go	Added GetDisplayName() utility and interface assertions for BaseMetadata.
mcp/types_test.go	Added tests for display name logic and Tool JSON serialization/deserialization.
examples/custom_context/main.go	Added Title to "make_authenticated_request" tool.
examples/dynamic_path/main.go	Added Title to "echo" tool.
examples/everything/main.go	Added Title fields to resources, templates, prompts, and tools; refactored resource creation to use titles.
examples/in_process/main.go	Added Title to "dummy_tool" tool.
examples/typed_tools/main.go	Added Title to "greeting" tool.

Assessment against linked issues

Objective	Addressed	Explanation
Create BaseMetadata interface with name and title (#418)	✅
Update Tool, Resource, Prompt, etc. to inherit from BaseMetadata (#418)	✅
Implement display name precedence: title → annotations.title → name (#418)	✅
Add helper functions for getting display names (#418)	✅
Update all examples to include title fields (#418)	✅	Titles added to tools, resources, prompts, and templates in multiple example files.

Assessment against linked issues: Out-of-scope changes

No out-of-scope changes found.

Possibly related PRs

• fix: tool annotation #165: Modifies Tool.MarshalJSON to include Annotations and adds test assertions for annotations; related to Tool metadata handling but focuses on annotations rather than Title.

Suggested labels

type: enhancement, area: sdk

Suggested reviewers

• ezynda3
• pottekkat

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (1.64.8)

Error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2
Failed executing command with error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2

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📒 Files selected for processing (5)

• examples/custom_context/main.go (1 hunks)
• examples/dynamic_path/main.go (1 hunks)
• examples/everything/main.go (6 hunks)
• examples/in_process/main.go (1 hunks)
• examples/typed_tools/main.go (1 hunks)

✅ Files skipped from review due to trivial changes (5)

• examples/typed_tools/main.go
• examples/in_process/main.go
• examples/custom_context/main.go
• examples/dynamic_path/main.go
• examples/everything/main.go

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• GitHub Check: test

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[pottekkat]

Do we need to have different functions like WithResourceTitle, WithPromptTitle, and WithTitle? Seems a bit unnecessary. Can we provide better APIs?

[davidleitw]

I feel that, at least for the DisplayName topic, we should try to provide helper functions to make it easier for users. Or do you have any good ideas regarding the API design? I’d be happy to try making some adjustments.