MCP Client SDK

MCP Server SDK

Misc

Prompts Development

AJ-MCP uses annotations to define prompts within @McpService classes. The @Prompt annotation marks methods that serve as prompt handlers, while @PromptArg defines parameters for interactive prompts.

Simple prompts return a single PromptMessage with text content. The @Prompt annotation requires a description and the method returns a configured message with role and content.

@Prompt(description = "Basic simple prompt")
public PromptMessage basic(){
        PromptMessage message=new PromptMessage();
        message.setRole(Role.USER);
        message.setContent(new ContentText("Hello"));

        return message;
        }

Multi-Message Prompts

Prompts can return multiple messages by returning a List<PromptMessage>. This enables creating conversation-style prompts with multiple turns or role-based interactions.

@Prompt(description = "Prompt that returns two messages")
public List<PromptMessage> multi(){
        PromptMessage message1=new PromptMessage();
        message1.setRole(Role.USER);
        message1.setContent(new ContentText("first"));

        PromptMessage message2=new PromptMessage();
        message2.setRole(Role.USER);
        message2.setContent(new ContentText("second"));

        return Arrays.asList(message1,message2);
        }

Parameterized Prompts

Prompts can accept parameters using the @PromptArg annotation. Parameters become available to clients when listing prompts and are passed when retrieving the prompt.

@Prompt(description = "Parametrized prompt")
public PromptMessage parametrized(@PromptArg(description = "The name") String name){
        PromptMessage message=new PromptMessage();
        message.setRole(Role.USER);
        message.setContent(new ContentText("Hello "+name));

        return message;
        }

Content Types and Rich Media

Prompts support multiple content types beyond text, including images and embedded resources. Each content type has specific properties and encoding requirements.

Content Type Class Key Properties Usage
Text ContentText text Simple text messages
Image ContentImage data, mimeType Base64-encoded images
Embedded Resource ContentEmbeddedResource resource.uri, resource.mimeType Binary data references

Protocol Data Structures

The prompt system uses specific protocol structures for communication between client and server.

Class Purpose Key Fields
PromptItem Prompt metadata for listing name, description, arguments
PromptMessage Individual message content role, content
GetPromptResult Response wrapper result.description, result.messages
PromptArgument Parameter definition name, description, required

Role Enumeration

The Role enum defines message roles in prompt conversations: