DeepSeek MCP Server

Implementation Reference

• src/index.ts:295-345 (handler)

  Handler function for multi_turn_chat tool that maintains persistent conversation history, transforms messages, calls DeepSeek API, updates history with response, and returns text content.

  async (args) => {
    try {
      // Transform new messages
      const newMessage = args.messages[0];
      const transformedNewMessage = {
        role: newMessage.role,
        content: newMessage.content.text
      };
  
      // Add new message to history
      this.conversationHistory.push(transformedNewMessage);
  
      // Transform all messages for API
      const transformedMessages = this.conversationHistory.map(msg => ({
        role: msg.role,
        content: msg.content
      }));
  
      const response = await this.axiosInstance.post<DeepSeekResponse>(
        API_CONFIG.ENDPOINTS.CHAT,
        {
          messages: transformedMessages,
          model: args.model,
          temperature: args.temperature,
          max_tokens: args.max_tokens,
          top_p: args.top_p,
          frequency_penalty: args.frequency_penalty,
          presence_penalty: args.presence_penalty
        }
      );
  
      // Add assistant's response to history
      const assistantMessage = {
        role: 'assistant' as const,
        content: response.data.choices[0].message.content
      };
      this.conversationHistory.push(assistantMessage);
  
      return {
        content: [{
          type: "text",
          text: assistantMessage.content
        }]
      };
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(`DeepSeek API error: ${error.response?.data?.error?.message ?? error.message}`);
      }
      throw error;
    }
  }

• src/index.ts:266-294 (schema)

  Zod input schema for multi_turn_chat tool, supporting string or structured messages with transformation, and various generation parameters.

  {
    messages: z.union([
      z.string(),
      z.array(z.object({
        role: z.enum(['system', 'user', 'assistant']),
        content: z.object({
          type: z.literal('text'),
          text: z.string()
        })
      }))
    ]).transform(messages => {
      if (typeof messages === 'string') {
        return [{
          role: 'user' as const,
          content: {
            type: 'text' as const,
            text: messages
          }
        }];
      }
      return messages;
    }),
    model: z.string().default('deepseek-chat'),
    temperature: z.number().min(0).max(2).default(0.7),
    max_tokens: z.number().positive().int().default(8000),
    top_p: z.number().min(0).max(1).default(1.0),
    frequency_penalty: z.number().min(-2).max(2).default(0.1),
    presence_penalty: z.number().min(-2).max(2).default(0)
  },

• src/index.ts:264-346 (registration)

  Registration of the multi_turn_chat tool on the MCP server using server.tool(name, inputSchema, handlerFn).

  this.server.tool(
    "multi_turn_chat",
    {
      messages: z.union([
        z.string(),
        z.array(z.object({
          role: z.enum(['system', 'user', 'assistant']),
          content: z.object({
            type: z.literal('text'),
            text: z.string()
          })
        }))
      ]).transform(messages => {
        if (typeof messages === 'string') {
          return [{
            role: 'user' as const,
            content: {
              type: 'text' as const,
              text: messages
            }
          }];
        }
        return messages;
      }),
      model: z.string().default('deepseek-chat'),
      temperature: z.number().min(0).max(2).default(0.7),
      max_tokens: z.number().positive().int().default(8000),
      top_p: z.number().min(0).max(1).default(1.0),
      frequency_penalty: z.number().min(-2).max(2).default(0.1),
      presence_penalty: z.number().min(-2).max(2).default(0)
    },
    async (args) => {
      try {
        // Transform new messages
        const newMessage = args.messages[0];
        const transformedNewMessage = {
          role: newMessage.role,
          content: newMessage.content.text
        };
  
        // Add new message to history
        this.conversationHistory.push(transformedNewMessage);
  
        // Transform all messages for API
        const transformedMessages = this.conversationHistory.map(msg => ({
          role: msg.role,
          content: msg.content
        }));
  
        const response = await this.axiosInstance.post<DeepSeekResponse>(
          API_CONFIG.ENDPOINTS.CHAT,
          {
            messages: transformedMessages,
            model: args.model,
            temperature: args.temperature,
            max_tokens: args.max_tokens,
            top_p: args.top_p,
            frequency_penalty: args.frequency_penalty,
            presence_penalty: args.presence_penalty
          }
        );
  
        // Add assistant's response to history
        const assistantMessage = {
          role: 'assistant' as const,
          content: response.data.choices[0].message.content
        };
        this.conversationHistory.push(assistantMessage);
  
        return {
          content: [{
            type: "text",
            text: assistantMessage.content
          }]
        };
      } catch (error) {
        if (axios.isAxiosError(error)) {
          throw new Error(`DeepSeek API error: ${error.response?.data?.error?.message ?? error.message}`);
        }
        throw error;
      }
    }
  );

• src/index.ts:92-92 (helper)

  Class property that stores the persistent conversation history used by the multi_turn_chat handler.

  private conversationHistory: ChatMessage[] = [];