```python
import sqlite3
from langchain.tools import tool

# Below are minimal tools for demonstration purposes.
# They are not intended to be secure or for production use.

@tool
def sql_db_list_tables() -> str:
    """Input is an empty string, output is a comma-separated list of tables in the database."""
    con = sqlite3.connect("Chinook.db")
    try:
        cursor = con.cursor()
        cursor.execute("SELECT name FROM sqlite_master WHERE type='table';")
        tables = [row[0] for row in cursor.fetchall() if not row[0].startswith("sqlite_")]
        return ", ".join(tables)
    finally:
        con.close()

@tool
def sql_db_schema(table_names: str) -> str:
    """Input to this tool is a comma-separated list of tables, output is the schema and sample rows for those tables.
    Be sure that the tables actually exist by calling sql_db_list_tables first!
    Example Input: table1, table2, table3"""
    con = sqlite3.connect("Chinook.db")
    try:
        cursor = con.cursor()
        cursor.execute("SELECT name FROM sqlite_master WHERE type='table';")
        valid_tables = {row[0] for row in cursor.fetchall() if not row[0].startswith("sqlite_")}
        results = []
        for table in table_names.split(","):
            table = table.strip()
            if table not in valid_tables:
                results.append(f"Error: table_names {{{table!r}}} not found in database")
                continue
            cursor.execute("SELECT sql FROM sqlite_master WHERE type='table' AND name=?;", (table,))
            schema_row = cursor.fetchone()
            if schema_row:
                results.append(schema_row[0])
                try:
                    quoted_table = '"' + table.replace('"', '""') + '"'
                    cursor.execute(f"SELECT * FROM {quoted_table} LIMIT 3;")
                    rows = cursor.fetchall()
                    if rows:
                        col_names = [description[0] for description in cursor.description]
                        results.append(
                            f"/*\n3 rows from {table} table:\n"
                            + "\t".join(col_names)
                            + "\n"
                            + "\n".join("\t".join(str(x) for x in row) for row in rows)
                            + "\n*/"
                        )
                except Exception as e:
                    results.append(f"Error fetching sample rows: {e}")
        return "\n\n".join(results)
    finally:
        con.close()

@tool
def sql_db_query(query: str) -> str:
    """Input to this tool is a detailed and correct SQL query, output is a result from the database.
    If the query is not correct, an error message will be returned.
    If an error is returned, rewrite the query, check the query, and try again.
    If you encounter an issue with Unknown column 'xxxx' in 'field list', use sql_db_schema to query the correct table fields."""
    con = sqlite3.connect("Chinook.db")
    try:
        cursor = con.cursor()
        cursor.execute(query)
        res = cursor.fetchall()
        return str(res)
    except Exception as e:
        return f"Error: {e}"
    finally:
        con.close()

@tool
def sql_db_query_checker(query: str) -> str:
    """Use this tool to double check if your query is correct before executing it.
    Always use this tool before executing a query with sql_db_query!"""
    trigger_prompt = """{query}
Double check the sqlite query above for common mistakes, including:
- Using NOT IN with NULL values
- Using UNION when UNION ALL should have been used
- Using BETWEEN for exclusive ranges
- Data type mismatch in predicates
- Properly quoting identifiers
- Using the correct number of arguments for functions
- Casting to the correct data type
- Using the proper columns for joins

If there are any of the above mistakes, rewrite the query. If there are no mistakes, just reproduce the original query.

Output the final SQL query only.

SQL Query: """.format(query=query)

    response = model.invoke(trigger_prompt)
    return response.text.strip()

tools = [sql_db_list_tables, sql_db_schema, sql_db_query, sql_db_query_checker]

# Use a distinct loop variable so it does not shadow the `tool` decorator.
for t in tools:
    print(f"{t.name}: {t.description}\n")
```
