Run analytical SQL on local CSV/JSON/Parquet files via mcp-server-duckdb (uvx)

{
  "server": "mcp-server-duckdb",
  "version": "1.27.2",
  "spawn": "uvx --from mcp-server-duckdb mcp-server-duckdb --db-path /tmp/pathfinder-test3.duckdb",
  "transport": "stdio",
  "framing": "NDJSON",
  "tools": ["query"],
  "trace": [
    {
      "step": "initialize",
      "request": {
        "jsonrpc": "2.0",
        "id": 1,
        "method": "initialize",
        "params": {
          "protocolVersion": "2024-11-05",
          "capabilities": {},
          "clientInfo": {
            "name": "pathfinder",
            "version": "1.0"
          }
        }
      },
      "response": {
        "serverInfo": {
          "name": "mcp-duckdb-server",
          "version": "1.27.2"
        },
        "protocolVersion": "2024-11-05"
      }
    },
    {
      "step": "tools/list",
      "request": {
        "jsonrpc": "2.0",
        "id": 2,
        "method": "tools/list",
        "params": {}
      },
      "response": {
        "tools": [
          {
            "name": "query",
            "inputSchema": {
              "type": "object",
              "properties": {
                "query": {
                  "type": "string"
                }
              },
              "required": ["query"]
            }
          }
        ]
      }
    },
    {
      "step": "query — CREATE+INSERT (in-memory)",
      "request": {
        "jsonrpc": "2.0",
        "id": 3,
        "method": "tools/call",
        "params": {
          "name": "query",
          "arguments": {
            "query": "CREATE TABLE cities (name TEXT, country TEXT, population INTEGER); INSERT INTO cities VALUES ('Tokyo','Japan',13960000),('Istanbul','Turkey',15460000),('London','UK',8982000),('Berlin','Germany',3645000),('Paris','France',2161000);"
          }
        }
      },
      "response": {
        "content": [
          {
            "type": "text",
            "text": "[(5,)]"
          }
        ],
        "isError": false
      }
    },
    {
      "step": "query — SELECT ORDER BY (in-memory)",
      "request": {
        "jsonrpc": "2.0",
        "id": 4,
        "method": "tools/call",
        "params": {
          "name": "query",
          "arguments": {
            "query": "SELECT name, country, population FROM cities ORDER BY population DESC;"
          }
        }
      },
      "response": {
        "content": [
          {
            "type": "text",
            "text": "[('Istanbul', 'Turkey', 15460000), ('Tokyo', 'Japan', 13960000), ('London', 'UK', 8982000), ('Berlin', 'Germany', 3645000), ('Paris', 'France', 2161000)]"
          }
        ],
        "isError": false
      }
    },
    {
      "step": "query — DESCRIBE read_csv_auto (file analytics)",
      "request": {
        "jsonrpc": "2.0",
        "id": 3,
        "method": "tools/call",
        "params": {
          "name": "query",
          "arguments": {
            "query": "DESCRIBE SELECT * FROM read_csv_auto('/tmp/sample-sales.csv');"
          }
        }
      },
      "response": {
        "content": [
          {
            "type": "text",
            "text": "[('date', 'DATE', 'YES', None, None, None), ('product', 'VARCHAR', 'YES', None, None, None), ('region', 'VARCHAR', 'YES', None, None, None), ('units', 'BIGINT', 'YES', None, None, None), ('revenue', 'DOUBLE', 'YES', None, None, None)]"
          }
        ],
        "isError": false
      }
    },
    {
      "step": "query — GROUP BY aggregation on CSV",
      "request": {
        "jsonrpc": "2.0",
        "id": 4,
        "method": "tools/call",
        "params": {
          "name": "query",
          "arguments": {
            "query": "SELECT product, SUM(units) as total_units, ROUND(SUM(revenue),2) as total_revenue FROM read_csv_auto('/tmp/sample-sales.csv') GROUP BY product ORDER BY total_revenue DESC;"
          }
        }
      },
      "response": {
        "content": [
          {
            "type": "text",
            "text": "[('Widget C', 600, 18000.0), ('Widget B', 420, 16800.0), ('Widget A', 545, 10900.0)]"
          }
        ],
        "isError": false
      }
    },
    {
      "step": "query — monthly trend with strftime",
      "request": {
        "jsonrpc": "2.0",
        "id": 5,
        "method": "tools/call",
        "params": {
          "name": "query",
          "arguments": {
            "query": "SELECT strftime(date::DATE, '%Y-%m') as month, COUNT(*) as transactions, SUM(units) as total_units, ROUND(SUM(revenue),2) as total_revenue FROM read_csv_auto('/tmp/sample-sales.csv') GROUP BY month ORDER BY month;"
          }
        }
      },
      "response": {
        "content": [
          {
            "type": "text",
            "text": "[('2026-01', 4, 500, 13700.0), ('2026-02', 4, 500, 17000.0), ('2026-03', 4, 565, 15000.0)]"
          }
        ],
        "isError": false
      }
    }
  ],
  "failure_report": {
    "ndjson_required": "Python MCP SDK uses NDJSON, not Content-Length. Content-Length framing causes pydantic ValidationError.",
    "wrong_param_name": "Tool param is 'query', not 'sql'. Using 'sql' returns Input validation error."
  },
  "executed_at": "2026-06-13T12:15:00Z"
}