Required additional mssql tools

### Prerequisites

- [x] Search the [current open issues](https://github.com/googleapis/mcp-toolbox/issues)

### What are you trying to do that currently feels hard or impossible?

kind: tool
name: execute_sql_tool
type: mssql-execute-sql
source: my-mssql-instance
description: Use this tool to execute sql statement.

### Suggested Solution(s)

_No response_

### Alternatives Considered

_No response_

### Additional Details

_No response_

Start by locating the existing database tool implementations and the configuration path for a source such as my-mssql-instance. Compare how an execute-SQL tool is defined and wired for supported databases, then determine the test or validation entry point for the new mssql-execute-sql type. Done means the tool can execute SQL against the named MSSQL source and its behavior is covered by the repository's existing checks.

Written by the indexing model from the issue text.