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UOM Orchestrator: MCP Database Toolbox & Schema Inspection

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1. The Role of MCP in Database Schema Inspection

• Microsoft SQL Server (Source): Retrieving table schemas, column types, primary keys, and foreign key relationships.
• Neo4j (Target): Inspecting node labels, relationship types, and properties.
• MongoDB (Target): Examining document structures, collection lists, and validators.

1. Generic Database Toolbox: Exposes tools for executing Cypher statements, viewing relational tables, and extracting metadata.
2. MongoDB MCP Server: Exposes collection-level management and query execution tools.

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2. Dynamic Configuration Synchronization (modify_toolbox_sources)

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2.1 The Localhost Resolution Problem

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2.2 Host Gateway Translation

• Default Gateway: Resolves to host.docker.internal (or a custom OUTER_HOST_GATEWAY_IP provided by the Daytona network bridge).
• MSSQL Connection Parsing: extract_mssql_connection_info parses the connection string using a strict regex pattern to extract connection parameters (host, port, database, user, password) needed to populate the MCP configuration:
  pattern = re.compile(
      r"Server=(?P<host>[^,;]+),(?P<port>\d+);Database=(?P<database>[^;]+);User Id=(?P<user>[^;]+);Password=(?P<password>[^;]+);?"
  )
  

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2.3 Overwriting settings Files Dynamically

db_toolbox_path = os.path.join(get_config_dir(), "db_toolbox", "custom_config.yaml")
data_sources = {
    "mssql-source": {
        "kind": "mssql",
        "host": mssql_conn_info["host"],
        "port": mssql_conn_info["port"],
        "database": mssql_conn_info["database"],
        "user": mssql_conn_info["user"],
        "password": mssql_conn_info["password"],
    },
    "neo4j-source": {
        "kind": "neo4j",
        "uri": translate_localhost_to_host_gateway(context.neo4j_uri),
        ...
    }
}
async with aiofiles.open(db_toolbox_path, "w") as f:
    await f.write(yaml.dump({"sources": data_sources}))

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3. Dynamic Tool Binding

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3.1 Loading Database Toolbox Tools (load_toolbox_tools)

• The loader connects to the server using the ToolboxClient SSE wrapper:
  async with ToolboxClient(toolbox_uri) as toolbox_client:
      toolbox_tools = await toolbox_client.aload_toolset()
  
• The loaded tools are cast to LangChain BaseTool objects and returned to the schema inspection node.

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3.2 Loading MongoDB Tools (load_mongodb_tools)

• To connect to the MongoDB MCP server, the loader instantiates a MultiServerMCPClient with tool_name_prefix=True:
  db_mcp_client = MultiServerMCPClient(
      {"mongodb": {"transport": "streamable_http", "url": mongodb_mcp_uri}},
      tool_name_prefix=True
  )
  async with db_mcp_client.session("mongodb") as db_mcp_session:
      db_tools = await load_mcp_tools(db_mcp_session)
  
• Enabling tool_name_prefix=True prefixes MongoDB tools with mongodb_ (e.g. mongodb_list_collections), preventing naming collisions with other tools.

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4. Exception Safety & Fallback Policies

• The database engine or Database Toolbox container might be temporarily down or starting up.
• Network glitches can trigger connection timeouts.
• Dynamic schema binding can raise BrokenResourceError in AnyIO sessions.

try:
    async with ToolboxClient(toolbox_uri) as toolbox_client:
        ...
        yield cast(list[BaseTool], toolbox_tools)
except* (BrokenResourceError, CancelledError, RuntimeError, Exception):
    logger.warning(
        "Failed to load database tools from toolbox server at %s. Proceeding without database tools.",
        toolbox_uri,
        exc_info=True
    )
    yield []

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4.1 Exception Group Filtering (except*)

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4.2 Graceful Failure Degradation

1. The tool loaders log a warning with the full stack trace for debugging.
2. They yield an empty list ([]) back to the schema inspection node.
3. The ReAct agent continues executing without access to schema tools.
4. The agent falls back to performing the translation using the user’s raw inputs and its static training data.