fix: Support GuardrailResult return type in guardrail functions (#875)

examples/guardrail_example_fixed.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+"""
+Fixed example demonstrating proper guardrail usage with PraisonAI Agents.
+This addresses the issues reported in issue #875.
+"""
+
+from praisonaiagents import Agent, Task, GuardrailResult, PraisonAIAgents, TaskOutput
+from typing import Tuple, Any
+import trafilatura
+
+# Example 1: Using GuardrailResult return type (now supported!)
+def validate_length_guardrailresult(output: TaskOutput) -> GuardrailResult:
+    """Ensure output is between 100-500 characters using GuardrailResult"""
+    # Extract the raw text from the TaskOutput object
+    text = output.raw if hasattr(output, 'raw') else str(output)
+    length = len(text)
+
+    if 100 <= length <= 500:
+        return GuardrailResult(
+            success=True,
+            result=output,  # Pass through the original output
+            error=""
+        )
+    else:
+        return GuardrailResult(
+            success=False,
+            result=None,
+            error=f"Output must be 100-500 chars, got {length}"
+        )
+
+# Example 2: Using Tuple[bool, Any] return type (original method)
+def validate_length_tuple(output: TaskOutput) -> Tuple[bool, Any]:
+    """Ensure output is between 100-500 characters using tuple"""
+    text = output.raw if hasattr(output, 'raw') else str(output)
+    length = len(text)
+
+    if 100 <= length <= 500:
+        return True, output
+    else:
+        return False, f"Output must be 100-500 chars, got {length}"
+
+# Tool function
+def get_url_context(url):
+    """Fetch and extract content from a URL"""
+    downloaded = trafilatura.fetch_url(url)
+    if not downloaded:
+        return "Sorry, I couldn't fetch the content from that URL."
+
+    extracted = trafilatura.extract(
+        downloaded,
+        include_comments=False,
+        include_links=True,
+        output_format='json',
+        with_metadata=True,
+        url=url
+    )
+
+    if not extracted:
+        return "Sorry, I couldn't extract readable content from that page."
+
+    return extracted  # returns JSON string
+
+# Create agent with FIXED tools parameter (must be a list!)
+agent = Agent(
+    name="Content Summarizer",
+    role="Content Analysis Expert",
+    goal="Summarize web content concisely",
+    instructions="You are a helpful assistant that summarizes web content",
+    llm="gemini/gemini-2.5-flash-lite-preview-06-17",
+    self_reflect=False,
+    verbose=True,
+    tools=[get_url_context]  # FIX: tools must be a list, not a single function
+)
+
+# Create task with GuardrailResult guardrail
+task_with_guardrailresult = Task(
+    name="summarise article with GuardrailResult",
+    description="get the context of this url: https://blog.google/technology/ai/dolphingemma/ and produce a summary below 500 characters",
+    agent=agent,
+    guardrail=validate_length_guardrailresult,  # Using GuardrailResult
+    expected_output="summary of the article below 500 characters",
+    max_retries=3  # Will retry up to 3 times if guardrail fails
+)
+
+# Alternative: Create task with tuple guardrail
+task_with_tuple = Task(
+    name="summarise article with tuple",
+    description="get the context of this url: https://blog.google/technology/ai/dolphingemma/ and produce a summary below 500 characters",
+    agent=agent,
+    guardrail=validate_length_tuple,  # Using Tuple[bool, Any]
+    expected_output="summary of the article below 500 characters",
+    max_retries=3
+)
+
+# Example with string-based LLM guardrail
+task_with_llm_guardrail = Task(
+    name="summarise with LLM guardrail",
+    description="get the context of this url: https://blog.google/technology/ai/dolphingemma/ and produce a summary",
+    agent=agent,
+    guardrail="Ensure the summary is professional, factual, and between 100-500 characters",
+    expected_output="professional summary of the article"
+)
+
+# Run with GuardrailResult example
+print("=== Running with GuardrailResult guardrail ===")
+agents_gr = PraisonAIAgents(
+    agents=[agent],
+    tasks=[task_with_guardrailresult]
+)
+
+# Uncomment to run:
+# result_gr = agents_gr.start()
+
+# Run with Tuple example
+print("\n=== Running with Tuple[bool, Any] guardrail ===")
+agents_tuple = PraisonAIAgents(
+    agents=[agent],
+    tasks=[task_with_tuple]
+)
+
+# Uncomment to run:
+# result_tuple = agents_tuple.start()
+
+# Run with LLM guardrail example
+print("\n=== Running with LLM-based guardrail ===")
+agents_llm = PraisonAIAgents(
+    agents=[agent],
+    tasks=[task_with_llm_guardrail]
+)
+
+# Uncomment to run:
+# result_llm = agents_llm.start()
+
+print("""
+Key fixes applied:
+1. GuardrailResult is now accepted as a valid return type annotation
+2. tools parameter must be a list: tools=[get_url_context] not tools=get_url_context
+3. Both GuardrailResult and Tuple[bool, Any] return types are supported
+4. String-based LLM guardrails are also supported
+
+The guardrail will automatically retry (up to max_retries times) if validation fails.
+""")

src/praisonai-agents/CLAUDE.md

@@ -139,10 +139,32 @@ task = Task(
 #### Task-Level Guardrails
 ```python
 from typing import Tuple, Any
+from praisonaiagents import GuardrailResult
 
-# Function-based guardrail
-def validate_output(task_output: TaskOutput) -> Tuple[bool, Any]:
-    """Custom validation function."""
+# Function-based guardrail (Option 1: Using GuardrailResult)
+def validate_output(task_output: TaskOutput) -> GuardrailResult:
+    """Custom validation function returning GuardrailResult."""
+    if "error" in task_output.raw.lower():
+        return GuardrailResult(
+            success=False,
+            result=None,
+            error="Output contains errors"
+        )
+    if len(task_output.raw) < 10:
+        return GuardrailResult(
+            success=False,
+            result=None,
+            error="Output is too short"
+        )
+    return GuardrailResult(
+        success=True,
+        result=task_output,
+        error=""
+    )
+
+# Function-based guardrail (Option 2: Using Tuple[bool, Any])
+def validate_output_tuple(task_output: TaskOutput) -> Tuple[bool, Any]:
+    """Custom validation function returning tuple."""
     if "error" in task_output.raw.lower():
         return False, "Output contains errors"
     if len(task_output.raw) < 10:
@@ -170,7 +192,27 @@ task = Task(
 #### Agent-Level Guardrails
 ```python
 # Agent guardrails apply to ALL outputs from that agent
-def validate_professional_tone(task_output: TaskOutput) -> Tuple[bool, Any]:
+
+# Option 1: Using GuardrailResult
+def validate_professional_tone(task_output: TaskOutput) -> GuardrailResult:
+    """Ensure professional tone in all agent responses."""
+    content = task_output.raw.lower()
+    casual_words = ['yo', 'dude', 'awesome', 'cool']
+    for word in casual_words:
+        if word in content:
+            return GuardrailResult(
+                success=False,
+                result=None,
+                error=f"Unprofessional language detected: {word}"
+            )
+    return GuardrailResult(
+        success=True,
+        result=task_output,
+        error=""
+    )
+
+# Option 2: Using Tuple[bool, Any]
+def validate_professional_tone_tuple(task_output: TaskOutput) -> Tuple[bool, Any]:
     """Ensure professional tone in all agent responses."""
     content = task_output.raw.lower()
     casual_words = ['yo', 'dude', 'awesome', 'cool']

src/praisonai-agents/praisonaiagents/task/task.py

@@ -172,8 +172,15 @@ def _setup_guardrail(self):
             # Check return annotation if present
             return_annotation = sig.return_annotation
             if return_annotation != inspect.Signature.empty:
+                # Import GuardrailResult for checking
+                from ..guardrails import GuardrailResult
+
+                # Check if it's a GuardrailResult type
+                is_guardrail_result = return_annotation is GuardrailResult
+
+                # Check for tuple return type
                 return_annotation_args = get_args(return_annotation)
-                if not (
+                is_tuple = (
                     get_origin(return_annotation) is tuple
                     and len(return_annotation_args) == 2
                     and return_annotation_args[0] is bool
@@ -183,9 +190,11 @@ def _setup_guardrail(self):
                         or return_annotation_args[1] is TaskOutput
                         or return_annotation_args[1] == Union[str, TaskOutput]
                     )
-                ):
+                )
+
+                if not (is_guardrail_result or is_tuple):
                     raise ValueError(
-                        "If return type is annotated, it must be Tuple[bool, Any]"
+                        "If return type is annotated, it must be GuardrailResult or Tuple[bool, Any]"
                     )
 
             self._guardrail_fn = self.guardrail
@@ -447,7 +456,11 @@ def _process_guardrail(self, task_output: TaskOutput):
             # Call the guardrail function
             result = self._guardrail_fn(task_output)
 
-            # Convert the result to a GuardrailResult
+            # Check if result is already a GuardrailResult
+            if isinstance(result, GuardrailResult):
+                return result
+
+            # Otherwise, convert the tuple result to a GuardrailResult
             return GuardrailResult.from_tuple(result)
 
         except Exception as e: