Gemini MCP Server

Instructions

Implementation Reference

• src/enhanced-stdio-server.ts:738-778 (handler)

  The core handler function for the 'list_models' tool. It filters the GEMINI_MODELS object based on the optional 'filter' parameter and returns a formatted list of available models as JSON text.

  private listModels(id: any, args: any): MCPResponse {
    const filter = args?.filter || 'all';
    let models = Object.entries(GEMINI_MODELS);
  
    if (filter !== 'all') {
      models = models.filter(([_, info]) => {
        switch (filter) {
          case 'thinking':
            return 'thinking' in info && info.thinking === true;
          case 'vision':
            return info.features.includes('function_calling'); // All current models support vision
          case 'grounding':
            return info.features.includes('grounding');
          case 'json_mode':
            return info.features.includes('json_mode');
          default:
            return true;
        }
      });
    }
  
    const modelList = models.map(([name, info]) => ({
      name,
      ...info
    }));
  
    return {
      jsonrpc: '2.0',
      id,
      result: {
        content: [{
          type: 'text',
          text: JSON.stringify(modelList, null, 2)
        }],
        metadata: {
          count: modelList.length,
          filter
        }
      }
    };
  }

• src/enhanced-stdio-server.ts:325-338 (registration)

  Tool registration in the getAvailableTools() method, which responds to tools/list requests. Defines the tool name, description, and input schema.

  {
    name: 'list_models',
    description: 'List all available Gemini models and their capabilities',
    inputSchema: {
      type: 'object',
      properties: {
        filter: {
          type: 'string',
          description: 'Filter models by capability',
          enum: ['all', 'thinking', 'vision', 'grounding', 'json_mode']
        }
      }
    }
  },

• src/enhanced-stdio-server.ts:328-337 (schema)

  Input schema definition for the 'list_models' tool, specifying the optional 'filter' parameter with allowed values.

  inputSchema: {
    type: 'object',
    properties: {
      filter: {
        type: 'string',
        description: 'Filter models by capability',
        enum: ['all', 'thinking', 'vision', 'grounding', 'json_mode']
      }
    }
  }

• src/enhanced-stdio-server.ts:12-61 (helper)

  Data structure of available Gemini models used by the list_models handler for generating the model list.

  const GEMINI_MODELS = {
    // Thinking models (2.5 series) - latest and most capable
    'gemini-2.5-pro': {
      description: 'Most capable thinking model, best for complex reasoning and coding',
      features: ['thinking', 'function_calling', 'json_mode', 'grounding', 'system_instructions'],
      contextWindow: 2000000, // 2M tokens
      thinking: true
    },
    'gemini-2.5-flash': {
      description: 'Fast thinking model with best price/performance ratio',
      features: ['thinking', 'function_calling', 'json_mode', 'grounding', 'system_instructions'],
      contextWindow: 1000000, // 1M tokens
      thinking: true
    },
    'gemini-2.5-flash-lite': {
      description: 'Ultra-fast, cost-efficient thinking model for high-throughput tasks',
      features: ['thinking', 'function_calling', 'json_mode', 'system_instructions'],
      contextWindow: 1000000,
      thinking: true
    },
    
    // 2.0 series
    'gemini-2.0-flash': {
      description: 'Fast, efficient model with 1M context window',
      features: ['function_calling', 'json_mode', 'grounding', 'system_instructions'],
      contextWindow: 1000000
    },
    'gemini-2.0-flash-lite': {
      description: 'Most cost-efficient model for simple tasks',
      features: ['function_calling', 'json_mode', 'system_instructions'],
      contextWindow: 1000000
    },
    'gemini-2.0-pro-experimental': {
      description: 'Experimental model with 2M context, excellent for coding',
      features: ['function_calling', 'json_mode', 'grounding', 'system_instructions'],
      contextWindow: 2000000
    },
    
    // Legacy models (for compatibility)
    'gemini-1.5-pro': {
      description: 'Previous generation pro model',
      features: ['function_calling', 'json_mode', 'system_instructions'],
      contextWindow: 2000000
    },
    'gemini-1.5-flash': {
      description: 'Previous generation fast model',
      features: ['function_calling', 'json_mode', 'system_instructions'],
      contextWindow: 1000000
    }
  };