Improve tool call validation strictness (#4190)

* Improve tool call validation strictness

Reject near-miss tool names without executing suggested tools. Require object-shaped tool parameters while preserving only lossless JSON wire-shape normalization.

* Tighten tool call argument validation

* Simplify tool argument validation tests

* Improve tool name suggestions

* Simplify tool suggestion helpers

* Limit tool suggestions to canonical matches

* Allow repair only for tool history replay

* Clarify non-object tool argument errors

* Inline replay tool argument normalization

* Track only successful tool executions

* Reject JSON null tool arguments

nanobot/agent/tools/registry.py

@@ -1,5 +1,6 @@
 """Tool registry for dynamic tool management."""
 
+import json
 from typing import Any
 
 from nanobot.agent.tools.base import Tool
@@ -30,6 +31,24 @@ class ToolRegistry:
         """Get a tool by name."""
         return self._tools.get(name)
 
+    @staticmethod
+    def _lookup_key(name: str) -> str:
+        """Normalize names for suggestions only; never for execution."""
+        return "".join(ch.lower() for ch in name if ch.isalnum())
+
+    def _suggest_name(self, name: str) -> str | None:
+        key = self._lookup_key(str(name or ""))
+        if not key:
+            return None
+        matches = [
+            registered
+            for registered in self._tools
+            if self._lookup_key(registered) == key
+        ]
+        if len(matches) == 1:
+            return matches[0]
+        return None
+
     def has(self, name: str) -> bool:
         """Check if a tool is registered."""
         return name in self._tools
@@ -73,20 +92,23 @@ class ToolRegistry:
     def prepare_call(
         self,
         name: str,
-        params: dict[str, Any],
-    ) -> tuple[Tool | None, dict[str, Any], str | None]:
+        params: Any,
+    ) -> tuple[Tool | None, Any, str | None]:
         """Resolve, cast, and validate one tool call."""
-        # Guard against invalid parameter types (e.g., list instead of dict)
-        if not isinstance(params, dict) and name in ('write_file', 'read_file'):
-            return None, params, (
-                f"Error: Tool '{name}' parameters must be a JSON object, got {type(params).__name__}. "
-                "Use named parameters: tool_name(param1=\"value1\", param2=\"value2\")"
-            )
-
         tool = self._tools.get(name)
         if not tool:
+            suggestion = self._suggest_name(str(name))
+            hint = f" Did you mean '{suggestion}'? Tool names must match exactly." if suggestion else ""
             return None, params, (
-                f"Error: Tool '{name}' not found. Available: {', '.join(self.tool_names)}"
+                f"Error: Tool '{name}' not found.{hint} Available: {', '.join(self.tool_names)}"
+            )
+
+        params = self._coerce_params(tool, params)
+        if not isinstance(params, dict):
+            return tool, params, (
+                f"Error: Tool '{name}' parameters must be a JSON object, got "
+                f"{type(params).__name__}. Use named parameters like "
+                'tool_name(param1="value1", param2="value2") matching the tool schema.'
             )
 
         cast_params = tool.cast_params(params)
@@ -97,21 +119,56 @@ class ToolRegistry:
             )
         return tool, cast_params, None
 
-    async def execute(self, name: str, params: dict[str, Any]) -> Any:
+    @classmethod
+    def _coerce_argument_value(cls, value: Any) -> Any:
+        if value is None:
+            return {}
+        if not isinstance(value, str):
+            return value
+
+        stripped = value.strip()
+        if not stripped:
+            return {}
+
+        if not stripped.startswith(("{", "[")):
+            return value
+
+        try:
+            parsed = json.loads(stripped)
+        except Exception:
+            return value
+
+        return parsed
+
+    @classmethod
+    def _coerce_params(cls, tool: Tool, params: Any) -> Any:
+        params = cls._coerce_argument_value(params)
+        return cls._unwrap_arguments_payload(tool, params)
+
+    @classmethod
+    def _unwrap_arguments_payload(cls, tool: Tool, params: Any) -> Any:
+        if not isinstance(params, dict) or set(params) != {"arguments"}:
+            return params
+        properties = (tool.parameters or {}).get("properties", {})
+        if isinstance(properties, dict) and "arguments" in properties:
+            return params
+        return cls._coerce_argument_value(params.get("arguments"))
+
+    async def execute(self, name: str, params: Any) -> Any:
         """Execute a tool by name with given parameters."""
-        _HINT = "\n\n[Analyze the error above and try a different approach.]"
+        hint = "\n\n[Analyze the error above and try a different approach.]"
         tool, params, error = self.prepare_call(name, params)
         if error:
-            return error + _HINT
+            return error + hint
 
         try:
             assert tool is not None  # guarded by prepare_call()
             result = await tool.execute(**params)
             if isinstance(result, str) and result.startswith("Error"):
-                return result + _HINT
+                return result + hint
             return result
         except Exception as e:
-            return f"Error executing {name}: {str(e)}" + _HINT
+            return f"Error executing {name}: {str(e)}" + hint
 
     @property
     def tool_names(self) -> list[str]: