list_databases

Instructions

Implementation Reference

• src/mcp_snowflake_server/server.py:64-96 (handler)

  The handler function for the 'list_databases' tool. It queries Snowflake's INFORMATION_SCHEMA.DATABASES to list databases, applies exclusion filters if provided, formats the output as YAML and JSON, and returns text content and an embedded JSON resource.

  async def handle_list_databases(arguments, db, *_, exclusion_config=None):
      query = "SELECT DATABASE_NAME FROM INFORMATION_SCHEMA.DATABASES"
      data, data_id = await db.execute_query(query)
  
      # Filter out excluded databases
      if exclusion_config and "databases" in exclusion_config and exclusion_config["databases"]:
          filtered_data = []
          for item in data:
              db_name = item.get("DATABASE_NAME", "")
              exclude = False
              for pattern in exclusion_config["databases"]:
                  if pattern.lower() in db_name.lower():
                      exclude = True
                      break
              if not exclude:
                  filtered_data.append(item)
          data = filtered_data
  
      output = {
          "type": "data",
          "data_id": data_id,
          "data": data,
      }
      yaml_output = data_to_yaml(output)
      json_output = json.dumps(output)
      return [
          types.TextContent(type="text", text=yaml_output),
          types.EmbeddedResource(
              type="resource",
              resource=types.TextResourceContents(uri=f"data://{data_id}", text=json_output, mimeType="application/json"),
          ),
      ]

• src/mcp_snowflake_server/server.py:427-435 (registration)

  Registration of the 'list_databases' tool in the all_tools list, including name, description, empty input schema (no arguments required), and reference to the handler function. This tool object is later filtered and exposed via handle_list_tools().

  Tool(
      name="list_databases",
      description="List all available databases in Snowflake",
      input_schema={
          "type": "object",
          "properties": {},
      },
      handler=handle_list_databases,
  ),

• src/mcp_snowflake_server/server.py:430-433 (schema)

  Input schema definition for the 'list_databases' tool, specifying an empty object (no required parameters).

  input_schema={
      "type": "object",
      "properties": {},
  },

• src/mcp_snowflake_server/server.py:598-622 (helper)

  The general call_tool handler includes special logic for 'list_databases' (and similar tools) to pass the exclusion_config parameter to enable filtering.

  @server.call_tool()
  @handle_tool_errors
  async def handle_call_tool(
      name: str, arguments: dict[str, Any] | None
  ) -> list[types.TextContent | types.ImageContent | types.EmbeddedResource]:
      if name in exclude_tools:
          return [types.TextContent(type="text", text=f"Tool {name} is excluded from this data connection")]
  
      handler = next((tool.handler for tool in allowed_tools if tool.name == name), None)
      if not handler:
          raise ValueError(f"Unknown tool: {name}")
  
      # Pass exclusion_config to the handler if it's a listing function
      if name in ["list_databases", "list_schemas", "list_tables"]:
          return await handler(
              arguments,
              db,
              write_detector,
              allow_write,
              server,
              exclusion_config=exclusion_config,
          )
      else:
          return await handler(arguments, db, write_detector, allow_write, server)