refactor: rename tool XML wrapper from tool_calls to tool_batch and add schema attention blocks to tool prompts

internal/adapter/claude/handler_util_test.go

@@ -319,7 +319,8 @@ func TestBuildClaudeToolPromptSupportsOpenAIStyleFunctionTool(t *testing.T) {
 				"name":        "search",
 				"description": "Search via function tool",
 				"parameters": map[string]any{
-					"type": "object",
+					"type":     "object",
+					"required": []any{"q"},
 					"properties": map[string]any{
 						"q": map[string]any{"type": "string"},
 					},
@@ -334,8 +335,8 @@ func TestBuildClaudeToolPromptSupportsOpenAIStyleFunctionTool(t *testing.T) {
 	if !containsStr(prompt, "Search via function tool") {
 		t.Fatalf("expected OpenAI-style function tool description in prompt, got: %q", prompt)
 	}
-	if !containsStr(prompt, "\"q\"") {
-		t.Fatalf("expected parameters schema serialized in prompt, got: %q", prompt)
+	if !containsStr(prompt, "MUST INCLUDE: q") {
+		t.Fatalf("expected required-field summary in prompt, got: %q", prompt)
 	}
 }
 

internal/adapter/claude/handler_utils.go

@@ -90,8 +90,7 @@ func buildClaudeToolPrompt(tools []any) string {
 			continue
 		}
 		names = append(names, name)
-		schema, _ := json.Marshal(schemaObj)
-		toolSchemas = append(toolSchemas, fmt.Sprintf("Tool: %s\nDescription: %s\nParameters: %s", name, desc, schema))
+		toolSchemas = append(toolSchemas, util.FormatToolSchemaAttentionBlock(name, desc, schemaObj))
 	}
 	if len(toolSchemas) == 0 {
 		return ""

internal/adapter/openai/handler_toolcall_format.go

@@ -2,7 +2,6 @@ package openai
 
 import (
 	"encoding/json"
-	"fmt"
 	"strings"
 
 	"github.com/google/uuid"
@@ -44,11 +43,7 @@ func injectToolPrompt(messages []map[string]any, tools []any, policy util.ToolCh
 			continue
 		}
 		names = append(names, name)
-		if desc == "" {
-			desc = "No description available"
-		}
-		b, _ := json.Marshal(schema)
-		toolSchemas = append(toolSchemas, fmt.Sprintf("Tool: %s\nDescription: %s\nParameters: %s", name, desc, string(b)))
+		toolSchemas = append(toolSchemas, util.FormatToolSchemaAttentionBlock(name, desc, schema))
 	}
 	if len(toolSchemas) == 0 {
 		return messages, names

internal/adapter/openai/prompt_build_test.go

@@ -34,7 +34,11 @@ func TestBuildOpenAIFinalPrompt_HandlerPathIncludesToolRoundtripSemantics(t *tes
 				"name":        "get_weather",
 				"description": "Get weather",
 				"parameters": map[string]any{
-					"type": "object",
+					"type":     "object",
+					"required": []any{"city"},
+					"properties": map[string]any{
+						"city": map[string]any{"type": "string"},
+					},
 				},
 			},
 		},
@@ -53,6 +57,9 @@ func TestBuildOpenAIFinalPrompt_HandlerPathIncludesToolRoundtripSemantics(t *tes
 	if !strings.Contains(finalPrompt, "<tool_name>get_weather</tool_name>") {
 		t.Fatalf("handler finalPrompt should include tool name history: %q", finalPrompt)
 	}
+	if !strings.Contains(finalPrompt, "MUST INCLUDE: city") {
+		t.Fatalf("handler finalPrompt should front-load required fields: %q", finalPrompt)
+	}
 }
 
 func TestBuildOpenAIFinalPrompt_VercelPreparePathKeepsFinalAnswerInstruction(t *testing.T) {
@@ -67,7 +74,11 @@ func TestBuildOpenAIFinalPrompt_VercelPreparePathKeepsFinalAnswerInstruction(t *
 				"name":        "search",
 				"description": "search docs",
 				"parameters": map[string]any{
-					"type": "object",
+					"type":     "object",
+					"required": []any{"query"},
+					"properties": map[string]any{
+						"query": map[string]any{"type": "string"},
+					},
 				},
 			},
 		},
@@ -83,6 +94,9 @@ func TestBuildOpenAIFinalPrompt_VercelPreparePathKeepsFinalAnswerInstruction(t *
 	if !strings.Contains(finalPrompt, "TOOL CALL FORMAT") {
 		t.Fatalf("vercel prepare finalPrompt missing xml format instruction: %q", finalPrompt)
 	}
+	if !strings.Contains(finalPrompt, "MUST INCLUDE: query") {
+		t.Fatalf("vercel prepare finalPrompt missing required-field summary: %q", finalPrompt)
+	}
 	if !strings.Contains(finalPrompt, "Do NOT wrap the XML in markdown code fences") {
 		t.Fatalf("vercel prepare finalPrompt missing no-fence xml instruction: %q", finalPrompt)
 	}