mssql_describe_table

Instructions

Implementation Reference

• src/index.ts:527-572 (handler)

  The handler function that executes the mssql_describe_table tool. It parses input arguments using ConnectionSchema, establishes a database connection, queries INFORMATION_SCHEMA.COLUMNS with a LEFT JOIN to identify primary keys, and returns structured JSON with table column details including name, type, nullability, default, lengths, precision, scale, and primary key status.

  private async handleDescribeTable(args: any) {
    const config = ConnectionSchema.parse(args);
    const { table } = args;
    const pool = await this.getConnection(config);
    
    const request = pool.request();
    const result = await request.query(`
      USE [${config.database}];
      SELECT 
        c.COLUMN_NAME as column_name,
        c.DATA_TYPE as data_type,
        c.IS_NULLABLE as is_nullable,
        c.COLUMN_DEFAULT as default_value,
        c.CHARACTER_MAXIMUM_LENGTH as max_length,
        c.NUMERIC_PRECISION as precision,
        c.NUMERIC_SCALE as scale,
        CASE WHEN pk.COLUMN_NAME IS NOT NULL THEN 'YES' ELSE 'NO' END as is_primary_key
      FROM INFORMATION_SCHEMA.COLUMNS c
      LEFT JOIN (
        SELECT ku.TABLE_CATALOG, ku.TABLE_SCHEMA, ku.TABLE_NAME, ku.COLUMN_NAME
        FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS tc
        INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS ku
          ON tc.CONSTRAINT_TYPE = 'PRIMARY KEY'
          AND tc.CONSTRAINT_NAME = ku.CONSTRAINT_NAME
      ) pk ON c.TABLE_CATALOG = pk.TABLE_CATALOG
        AND c.TABLE_SCHEMA = pk.TABLE_SCHEMA
        AND c.TABLE_NAME = pk.TABLE_NAME
        AND c.COLUMN_NAME = pk.COLUMN_NAME
      WHERE c.TABLE_NAME = '${table}'
      ORDER BY c.ORDINAL_POSITION
    `);
  
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify({
            server: config.server,
            database: config.database,
            table: table,
            columns: result.recordset,
          }, null, 2),
        },
      ],
    };
  }

• src/index.ts:308-320 (schema)

  Input schema definition for the mssql_describe_table tool, specifying properties like server, port, credentials, database, table, and connection options, with required fields enforced.

  inputSchema: {
    type: 'object',
    properties: {
      server: { type: 'string', description: 'MSSQL Server hostname or IP address' },
      port: { type: 'number', description: 'Port number (default: 1433)', default: 1433 },
      user: { type: 'string', description: 'Username for authentication' },
      password: { type: 'string', description: 'Password for authentication' },
      database: { type: 'string', description: 'Database name' },
      table: { type: 'string', description: 'Table name' },
      encrypt: { type: 'boolean', description: 'Use encrypted connection (default: true)', default: true },
      trustServerCertificate: { type: 'boolean', description: 'Trust server certificate (default: true)', default: true },
    },
    required: ['server', 'user', 'password', 'database', 'table'],

• src/index.ts:305-322 (registration)

  Tool registration in the ListTools response, defining the name, description, and input schema for mssql_describe_table.

  {
    name: 'mssql_describe_table',
    description: 'Get detailed information about a table structure',
    inputSchema: {
      type: 'object',
      properties: {
        server: { type: 'string', description: 'MSSQL Server hostname or IP address' },
        port: { type: 'number', description: 'Port number (default: 1433)', default: 1433 },
        user: { type: 'string', description: 'Username for authentication' },
        password: { type: 'string', description: 'Password for authentication' },
        database: { type: 'string', description: 'Database name' },
        table: { type: 'string', description: 'Table name' },
        encrypt: { type: 'boolean', description: 'Use encrypted connection (default: true)', default: true },
        trustServerCertificate: { type: 'boolean', description: 'Trust server certificate (default: true)', default: true },
      },
      required: ['server', 'user', 'password', 'database', 'table'],
    },
  },

• src/index.ts:441-442 (registration)

  Dispatch registration in the CallToolRequest handler switch statement that routes calls to the mssql_describe_table handler function.

  case 'mssql_describe_table':
    return await this.handleDescribeTable(args);