Supported Return Types

This page lists the return types supported for each kind of handler. Use these so the annotation processor and runtime can serialize and expose results correctly.

Tools

• String
• McpSchema.CallToolResult
• McpSchema.Content
• McpSchema.TextContent
• POJO (serialized to JSON)

Prompts

• McpSchema.GetPromptResult
• McpSchema.PromptMessage
• List<McpSchema.PromptMessage>
• McpSchema.Content
• String
• POJO (string representation via toString())

Resources and Resource Templates

• McpSchema.ReadResourceResult
• McpSchema.ResourceContents
• List<McpSchema.ResourceContents>
• McpSchema.TextResourceContents
• McpSchema.BlobResourceContents
• POJO (serialized to JSON)

Completions

• McpSchema.CompleteResult
• McpSchema.CompleteResult.CompleteCompletion
• List<String>
• String