refactor(cot_agent): improve ReAct prompt clarity and format specification (#2478)

- Simplify format instructions for better LLM understanding
- Clarify when to use Action: vs FinalAnswer: prefixes
- Add multi-parameter example in action_input format
- Fix misleading 'always json' requirement in prompt
- Optimize prompt structure for better tool call accuracy

Author: whhe

agent-strategies/cot_agent/manifest.yaml

@@ -1,4 +1,4 @@
-version: 0.0.30
+version: 0.0.31
 type: plugin
 author: "langgenius"
 name: "agent"

agent-strategies/cot_agent/prompt/template.py

@@ -18,15 +18,13 @@
 
 Follow this format:
 
-Question: input question to answer
-Thought: consider previous and subsequent steps
-Action: $JSON_BLOB
-Observation: action result
-... (repeat Thought/Action/Observation N times)
-Thought: I know what to respond
-FinalAnswer: final response to human
-
-Begin! Reminder to ALWAYS respond with a valid json blob of a single action. Use tools if necessary. Respond directly if appropriate. Format is Action: $JSON_BLOB then Observation:.
+Thought: [your reasoning]
+Action: {"action": "tool_name", "action_input": {"param": "value"}}
+Observation: [tool output]
+... (repeat as needed)
+FinalAnswer: [your response]
+
+Begin! Use "Action:" only when calling tools. End with "FinalAnswer:".
 {{historic_messages}}
 Question: {{query}}
 {{agent_scratchpad}}
@@ -56,15 +54,13 @@
 
 Follow this format:
 
-Question: input question to answer
-Thought: consider previous and subsequent steps
-Action: $JSON_BLOB
-Observation: action result
-... (repeat Thought/Action/Observation N times)
-Thought: I know what to respond
-FinalAnswer: final response to human
+Thought: [your reasoning]
+Action: {"action": "tool_name", "action_input": {"param": "value"}}
+Observation: [tool output]
+... (repeat as needed)
+FinalAnswer: [your response]
 
-Begin! Reminder to ALWAYS respond with a valid json blob of a single action. Use tools if necessary. Respond directly if appropriate. Format is Action: $JSON_BLOB then Observation:.
+Begin! Use "Action:" only when calling tools. End with "FinalAnswer:".
 """  # noqa: E501