fix: add tool_info schema discovery for WASM tools (#1086)

* fix: add tool_info schema discovery for WASM tools

* refactor: simplify WASM schema and hint state

* refactor: store tool_info registry reference as Weak

src/tools/tool.rs

@@ -336,6 +336,17 @@ pub trait Tool: Send + Sync {
         None
     }
 
+    /// Full parameter schema for discovery and coercion purposes.
+    ///
+    /// Unlike `parameters_schema()` (which may be permissive to keep the tools
+    /// array compact), this returns the complete typed schema. Used by the
+    /// `tool_info` built-in and by WASM parameter coercion.
+    ///
+    /// Default: delegates to `parameters_schema()`.
+    fn discovery_schema(&self) -> serde_json::Value {
+        self.parameters_schema()
+    }
+
     /// Get the tool schema for LLM function calling.
     fn schema(&self) -> ToolSchema {
         ToolSchema {