Adding new tool usage and parsing logic

src/crewai/agents/parser.py

@@ -0,0 +1,61 @@
+from typing import Union
+
+from langchain.agents.output_parsers import ReActSingleInputOutputParser
+from langchain_core.agents import AgentAction, AgentFinish
+from langchain_core.exceptions import OutputParserException
+
+from crewai.utilities import I18N
+
+TOOL_USAGE_SECTION = "Use Tool:"
+FINAL_ANSWER_ACTION = "Final Answer:"
+FINAL_ANSWER_AND_TOOL_ERROR_MESSAGE = "You are trying to use a tool and give a final answer at the same time, choose only one."
+
+
+class CrewAgentParser(ReActSingleInputOutputParser):
+    """Parses Crew-style LLM calls that have a single tool input.
+
+    Expects output to be in one of two formats.
+
+    If the output signals that an action should be taken,
+    should be in the below format. This will result in an AgentAction
+    being returned.
+
+    ```
+    Use Tool: All context for using the tool here
+    ```
+
+    If the output signals that a final answer should be given,
+    should be in the below format. This will result in an AgentFinish
+    being returned.
+
+    ```
+    Final Answer: The temperature is 100 degrees
+    ```
+    """
+
+    _i18n: I18N = I18N()
+
+    def parse(self, text: str) -> Union[AgentAction, AgentFinish]:
+        includes_answer = FINAL_ANSWER_ACTION in text
+        includes_tool = TOOL_USAGE_SECTION in text
+
+        if includes_tool:
+            if includes_answer:
+                raise OutputParserException(f"{FINAL_ANSWER_AND_TOOL_ERROR_MESSAGE}")
+
+            return AgentAction("", "", text)
+
+        elif includes_answer:
+            return AgentFinish(
+                {"output": text.split(FINAL_ANSWER_ACTION)[-1].strip()}, text
+            )
+
+        error = self._i18n.errors("unexpected_format")
+        format = self._i18n.slice("format_without_tools")
+        error = f"{error}\n{format}"
+        raise OutputParserException(
+            error,
+            observation=error,
+            llm_output=text,
+            send_to_llm=True,
+        )