feat: add JSON schema validation to config_to_agent

- Add jsonschema dependency for configuration validation
- Implement JSON schema based on supported configuration keys
- Provide detailed validation error messages with field paths
- Add validation tests for invalid fields, types, and tool items
- Support null values for optional fields (model, prompt, name)
- Reject additional properties not in the schema
- All 14 tests passing including new validation tests

🤖 Assisted by Amazon Q Developer

Author: mrlee-amazon

pyproject.toml

@@ -30,6 +30,7 @@ dependencies = [
     "boto3>=1.26.0,<2.0.0",
     "botocore>=1.29.0,<2.0.0",
     "docstring_parser>=0.15,<1.0",
+    "jsonschema>=4.0.0,<5.0.0",
     "mcp>=1.11.0,<2.0.0",
     "pydantic>=2.4.0,<3.0.0",
     "typing-extensions>=4.13.2,<5.0.0",

src/strands/experimental/agent_config.py

@@ -6,8 +6,45 @@
 import json
 from pathlib import Path
 
+import jsonschema
+from jsonschema import ValidationError
+
 from ..agent import Agent
 
+# JSON Schema for agent configuration
+AGENT_CONFIG_SCHEMA = {
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "Agent Configuration",
+    "description": "Configuration schema for creating agents",
+    "type": "object",
+    "properties": {
+        "name": {
+            "description": "Name of the agent",
+            "type": ["string", "null"],
+            "default": None
+        },
+        "model": {
+            "description": "The model ID to use for this agent. If not specified, uses the default model.",
+            "type": ["string", "null"],
+            "default": None
+        },
+        "prompt": {
+            "description": "The system prompt for the agent. Provides high level context to the agent.",
+            "type": ["string", "null"],
+            "default": None
+        },
+        "tools": {
+            "description": "List of tools the agent can use. Can be module paths, file paths, or tool names.",
+            "type": "array",
+            "items": {
+                "type": "string"
+            },
+            "default": []
+        }
+    },
+    "additionalProperties": False
+}
+
 
 def config_to_agent(config: str | dict[str, any], **kwargs) -> Agent:
     """Create an Agent from a configuration file or dictionary.
@@ -56,6 +93,14 @@ def config_to_agent(config: str | dict[str, any], **kwargs) -> Agent:
     else:
         raise ValueError("Config must be a file path string or dictionary")
 
+    # Validate configuration against schema
+    try:
+        jsonschema.validate(config_dict, AGENT_CONFIG_SCHEMA)
+    except ValidationError as e:
+        # Provide more detailed error message
+        error_path = " -> ".join(str(p) for p in e.absolute_path) if e.absolute_path else "root"
+        raise ValueError(f"Configuration validation error at {error_path}: {e.message}") from e
+    
     # Prepare Agent constructor arguments
     agent_kwargs = {}
 

tests/strands/experimental/test_agent_config.py

@@ -112,3 +112,21 @@ def test_config_to_agent_ignores_none_values(self):
         agent = config_to_agent(config)
         assert agent.model.config["model_id"] == "test-model"
         # Agent should use its defaults for None values
+
+    def test_config_to_agent_validation_error_invalid_field(self):
+        """Test that invalid fields raise validation errors."""
+        config = {"model": "test-model", "invalid_field": "value"}
+        with pytest.raises(ValueError, match="Configuration validation error"):
+            config_to_agent(config)
+
+    def test_config_to_agent_validation_error_wrong_type(self):
+        """Test that wrong field types raise validation errors."""
+        config = {"model": "test-model", "tools": "not-a-list"}
+        with pytest.raises(ValueError, match="Configuration validation error"):
+            config_to_agent(config)
+
+    def test_config_to_agent_validation_error_invalid_tool_item(self):
+        """Test that invalid tool items raise validation errors."""
+        config = {"model": "test-model", "tools": ["valid-tool", 123]}
+        with pytest.raises(ValueError, match="Configuration validation error"):
+            config_to_agent(config)