MySql MCP Server

Instructions

Implementation Reference

• src/index.ts:507-541 (handler)

  The handler for the 'use_database' tool. It extracts the database name from arguments, validates it, executes a 'USE ??' query with the name as parameter, updates the connectionConfig.database, and returns a success message or error.

  case "use_database": {
    try {
      const dbName = request.params.arguments?.database as string;
  
      if (!dbName) {
        throw new Error("Database name is required");
      }
  
      await executeQuery("USE ??", [dbName]);
      connectionConfig.database = dbName;
  
      return {
        content: [
          {
            type: "text",
            text: `Successfully switched to database: ${dbName}`
          }
        ],
        isError: false
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text:
              error instanceof Error
                ? error.message
                : "Unknown error occurred"
          }
        ],
        isError: true
      };
    }
  }

• src/index.ts:245-258 (schema)

  Tool schema definition including name, description, and input schema for 'use_database' tool, registered in the ListTools response.

  {
    name: "use_database",
    description: "Switch to a different database.",
    inputSchema: {
      type: "object",
      properties: {
        database: {
          type: "string",
          description: "Name of the database to switch to"
        }
      },
      required: ["database"]
    }
  },

• src/index.ts:136-276 (registration)

  Registration of all tools including 'use_database' in the ListToolsRequestSchema handler.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return {
      tools: [
        {
          name: "status",
          description: "Check the current database connection status.",
          inputSchema: {
            type: "object",
            properties: {
              random_string: {
                type: "string",
                description: "Dummy parameter for no-parameter tools"
              }
            },
            required: ["random_string"]
          }
        },
        {
          name: "connect",
          description: "Connect to a MySQL database.",
          inputSchema: {
            type: "object",
            properties: {
              host: {
                type: "string",
                description: "Database server hostname or IP address"
              },
              port: { type: "string", description: "Database server port" },
              user: { type: "string", description: "Database username" },
              password: { type: "string", description: "Database password" },
              database: {
                type: "string",
                description: "Database name to connect to"
              }
            }
          }
        },
        {
          name: "disconnect",
          description: "Close the current MySQL database connection.",
          inputSchema: {
            type: "object",
            properties: {
              random_string: {
                type: "string",
                description: "Dummy parameter for no-parameter tools"
              }
            },
            required: ["random_string"]
          }
        },
        {
          name: "query",
          description: "Execute an SQL query on the connected database.",
          inputSchema: {
            type: "object",
            properties: {
              sql: { type: "string", description: "SQL query to execute" },
              params: {
                type: "array",
                description: "Parameters for prepared statements",
                items: { type: "string" }
              }
            },
            required: ["sql"]
          }
        },
        {
          name: "list_tables",
          description: "Get a list of tables in the current database.",
          inputSchema: {
            type: "object",
            properties: {
              random_string: {
                type: "string",
                description: "Dummy parameter for no-parameter tools"
              }
            },
            required: ["random_string"]
          }
        },
        {
          name: "describe_table",
          description: "Get the structure of a specific table.",
          inputSchema: {
            type: "object",
            properties: {
              table: {
                type: "string",
                description: "Name of the table to describe"
              }
            },
            required: ["table"]
          }
        },
        {
          name: "list_databases",
          description: "Get a list of all accessible databases on the server.",
          inputSchema: {
            type: "object",
            properties: {
              random_string: {
                type: "string",
                description: "Dummy parameter for no-parameter tools"
              }
            },
            required: ["random_string"]
          }
        },
        {
          name: "use_database",
          description: "Switch to a different database.",
          inputSchema: {
            type: "object",
            properties: {
              database: {
                type: "string",
                description: "Name of the database to switch to"
              }
            },
            required: ["database"]
          }
        },
        {
          name: "set_readonly",
          description: "Enable or disable read-only mode",
          inputSchema: {
            type: "object",
            properties: {
              readonly: {
                type: "boolean",
                description:
                  "Set to true to enable read-only mode, false to disable"
              }
            },
            required: ["readonly"]
          }
        }
      ]
    };
  });