dify/api/core/tools/mcp_tool/tool.py

import base64
import json
from collections.abc import Generator
from typing import Any

from core.mcp.error import MCPAuthError, MCPConnectionError
from core.mcp.mcp_client import MCPClient
from core.mcp.types import ImageContent, TextContent
from core.tools.__base.tool import Tool
from core.tools.__base.tool_runtime import ToolRuntime
from core.tools.entities.tool_entities import ToolEntity, ToolInvokeMessage, ToolProviderType


class MCPTool(Tool):
    def __init__(
        self,
        entity: ToolEntity,
        runtime: ToolRuntime,
        tenant_id: str,
        icon: str,
        server_url: str,
        provider_id: str,
        headers: dict[str, str] | None = None,
        timeout: float | None = None,
        sse_read_timeout: float | None = None,
    ):
        super().__init__(entity, runtime)
        self.tenant_id = tenant_id
        self.icon = icon
        self.server_url = server_url
        self.provider_id = provider_id
        self.headers = headers or {}
        self.timeout = timeout
        self.sse_read_timeout = sse_read_timeout

    def tool_provider_type(self) -> ToolProviderType:
        return ToolProviderType.MCP

    def _invoke(
        self,
        user_id: str,
        tool_parameters: dict[str, Any],
        conversation_id: str | None = None,
        app_id: str | None = None,
        message_id: str | None = None,
    ) -> Generator[ToolInvokeMessage, None, None]:
        from core.tools.errors import ToolInvokeError

        try:
            with MCPClient(
                self.server_url,
                self.provider_id,
                self.tenant_id,
                authed=True,
                headers=self.headers,
                timeout=self.timeout,
                sse_read_timeout=self.sse_read_timeout,
            ) as mcp_client:
                tool_parameters = self._handle_none_parameter(tool_parameters)
                result = mcp_client.invoke_tool(tool_name=self.entity.identity.name, tool_args=tool_parameters)
        except MCPAuthError as e:
            raise ToolInvokeError("Please auth the tool first") from e
        except MCPConnectionError as e:
            raise ToolInvokeError(f"Failed to connect to MCP server: {e}") from e
        except Exception as e:
            raise ToolInvokeError(f"Failed to invoke tool: {e}") from e

        for content in result.content:
            if isinstance(content, TextContent):
                yield from self._process_text_content(content)
            elif isinstance(content, ImageContent):
                yield self._process_image_content(content)

    def _process_text_content(self, content: TextContent) -> Generator[ToolInvokeMessage, None, None]:
        """Process text content and yield appropriate messages."""
        try:
            content_json = json.loads(content.text)
            yield from self._process_json_content(content_json)
        except json.JSONDecodeError:
            yield self.create_text_message(content.text)

    def _process_json_content(self, content_json: Any) -> Generator[ToolInvokeMessage, None, None]:
        """Process JSON content based on its type."""
        if isinstance(content_json, dict):
            yield self.create_json_message(content_json)
        elif isinstance(content_json, list):
            yield from self._process_json_list(content_json)
        else:
            # For primitive types (str, int, bool, etc.), convert to string
            yield self.create_text_message(str(content_json))

    def _process_json_list(self, json_list: list) -> Generator[ToolInvokeMessage, None, None]:
        """Process a list of JSON items."""
        if any(not isinstance(item, dict) for item in json_list):
            # If the list contains any non-dict item, treat the entire list as a text message.
            yield self.create_text_message(str(json_list))
            return

        # Otherwise, process each dictionary as a separate JSON message.
        for item in json_list:
            yield self.create_json_message(item)

    def _process_image_content(self, content: ImageContent) -> ToolInvokeMessage:
        """Process image content and return a blob message."""
        return self.create_blob_message(blob=base64.b64decode(content.data), meta={"mime_type": content.mimeType})

    def fork_tool_runtime(self, runtime: ToolRuntime) -> "MCPTool":
        return MCPTool(
            entity=self.entity,
            runtime=runtime,
            tenant_id=self.tenant_id,
            icon=self.icon,
            server_url=self.server_url,
            provider_id=self.provider_id,
            headers=self.headers,
            timeout=self.timeout,
            sse_read_timeout=self.sse_read_timeout,
        )

    def _handle_none_parameter(self, parameter: dict[str, Any]) -> dict[str, Any]:
        """
        in mcp tool invoke, if the parameter is empty, it will be set to None
        """
        return {
            key: value
            for key, value in parameter.items()
            if value is not None and not (isinstance(value, str) and value.strip() == "")
        }