Gemini MCP Server

Instructions

Implementation Reference

• src/tools/generate-text.ts:26-37 (handler)

  The main handler function that executes the generate_text tool. It takes the prompt, model, temperature, maxOutputTokens, and systemInstruction parameters, calls Google Gemini's generateContent API, and returns the text response or a formatted error.

  async ({ prompt, model, temperature, maxOutputTokens, systemInstruction }) => {
    try {
      const response = await ai.models.generateContent({
        model,
        contents: prompt,
        config: { temperature, maxOutputTokens, systemInstruction },
      });
      return { content: [{ type: 'text' as const, text: response.text ?? '' }] };
    } catch (error) {
      return formatToolError(error);
    }
  },

• src/tools/generate-text.ts:13-19 (schema)

  Input schema definition using zod for the generate_text tool. Defines required fields (prompt, model) and optional fields (temperature, maxOutputTokens, systemInstruction) with their validation rules and descriptions.

  inputSchema: {
    prompt: z.string().min(1).describe('The text prompt to send to Gemini'),
    model: TextModel.default('gemini-2.5-flash').describe('Gemini model to use'),
    temperature: z.number().min(0).max(2).optional().describe('Sampling temperature (0-2)'),
    maxOutputTokens: z.number().min(1).optional().describe('Maximum number of output tokens'),
    systemInstruction: z.string().optional().describe('System instruction to guide model behavior'),
  },

• src/index.ts:25-25 (registration)

  Registration of the generate_text tool with the MCP server. Calls the register function from generate-text.ts passing the server and AI client instances.

  registerGenerateText(server, ai);

• src/utils/errors.ts:1-7 (helper)

  Helper utility function used by generate_text handler to format errors. Converts errors to the standard MCP response format with isError flag.

  export function formatToolError(error: unknown) {
    const text = error instanceof Error ? error.message : String(error);
    return {
      content: [{ type: 'text' as const, text }],
      isError: true,
    };
  }

• src/types.ts:3-10 (schema)

  Type definition for TextModel enum used by generate_text schema. Defines valid Gemini model names including 'gemini-2.5-flash', 'gemini-2.5-pro', and various preview models.

  export const TextModel = z.enum([
    'gemini-2.5-flash',
    'gemini-2.5-pro',
    'gemini-3-flash-preview',
    'gemini-3-pro-preview',
    'gemini-3.1-pro-preview',
  ]);
  export type TextModel = z.infer<typeof TextModel>;