Polybrain MCP Server

Instructions

Implementation Reference

• src/mcp-tools.ts:220-269 (handler)

  The handler function for the 'conversation_history' tool. It retrieves the conversation state and history using ConversationManager and returns them as a JSON string in the MCP response format.

  async ({ conversationId }) => {
    try {
      const conversation = conversationManager.getConversationState(conversationId);
      if (!conversation) {
        return {
          content: [
            {
              type: "text" as const,
              text: `Error: Conversation not found: ${conversationId}`,
            },
          ],
        };
      }
  
      const history = conversationManager.getHistory(conversationId);
  
      logger.debug("Retrieved conversation history", {
        conversationId,
        messageCount: history.length,
      });
  
      return {
        content: [
          {
            type: "text" as const,
            text: JSON.stringify({
              conversationId,
              modelId: conversation.modelId,
              messages: history,
            }),
          },
        ],
      };
    } catch (error) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      logger.error(
        "Conversation history tool error",
        error instanceof Error ? error : new Error(errorMessage)
      );
  
      return {
        content: [
          {
            type: "text" as const,
            text: `Error: ${errorMessage}`,
          },
        ],
      };
    }
  }

• src/mcp-tools.ts:206-270 (registration)

  Registration of the 'conversation_history' tool on the MCP server, including title, description, input schema (Zod), and reference to the handler function.

  server.registerTool(
    "conversation_history",
    {
      title: "Review Your Conversation with Another Model",
      description:
        "See what you've already discussed with a specific model. Useful for understanding context before continuing a conversation, reviewing advice you got, or checking previous responses. Long conversations are automatically shortened to save context.",
      inputSchema: z.object({
        conversationId: z
          .string()
          .describe(
            "The ID of the conversation you want to review. Get this from the response of the chat tool when you first talk to a model."
          ),
      }),
    },
    async ({ conversationId }) => {
      try {
        const conversation = conversationManager.getConversationState(conversationId);
        if (!conversation) {
          return {
            content: [
              {
                type: "text" as const,
                text: `Error: Conversation not found: ${conversationId}`,
              },
            ],
          };
        }
  
        const history = conversationManager.getHistory(conversationId);
  
        logger.debug("Retrieved conversation history", {
          conversationId,
          messageCount: history.length,
        });
  
        return {
          content: [
            {
              type: "text" as const,
              text: JSON.stringify({
                conversationId,
                modelId: conversation.modelId,
                messages: history,
              }),
            },
          ],
        };
      } catch (error) {
        const errorMessage = error instanceof Error ? error.message : String(error);
        logger.error(
          "Conversation history tool error",
          error instanceof Error ? error : new Error(errorMessage)
        );
  
        return {
          content: [
            {
              type: "text" as const,
              text: `Error: ${errorMessage}`,
            },
          ],
        };
      }
    }
  );

• src/types.ts:47-51 (schema)

  TypeScript interface defining the structure of the conversation history response, matching the JSON returned by the handler.

  export interface ConversationHistoryResponse {
    conversationId: string;
    modelId: string;
    messages: ChatMessage[];
  }

• src/conversation-manager.ts:62-69 (helper)

  Helper method in ConversationManager that retrieves and truncates the message history for a given conversation ID. Used by the tool handler.

  getHistory(conversationId: string): ChatMessage[] {
    const conversation = this.conversations.get(conversationId);
    if (!conversation) {
      throw new Error(`Conversation not found: ${conversationId}`);
    }
  
    return this.truncateMessages(conversation.messages);
  }

• src/conversation-manager.ts:105-107 (helper)

  Helper method in ConversationManager that gets the full conversation state (including modelId) for a given conversation ID. Used by the tool handler.

  getConversationState(conversationId: string): ConversationState | null {
    return this.getConversation(conversationId);
  }