feat: refactor tool result summary handling by introducing BuildReducedToolResultSummary and updating related methods

internal/ai/runtime/internal/impl/adapter/mcp_tool_adapter.go

@@ -62,7 +62,7 @@ func (t *MCPTool) InvokableRun(ctx context.Context, argumentsInJSON string, opts
 	if err != nil {
 		return "", err
 	}
-	return buildToolResultSummary(result), nil
+	return BuildReducedToolResultSummary(result), nil
 }
 
 func buildToolInfo(definition MCPToolDefinition, metadata *mcps.ToolInfo) *schema.ToolInfo {
@@ -146,37 +146,6 @@ func mergeFixedArguments(arguments map[string]any, fixedArgs map[string]string)
 	return ret
 }
 
-func buildToolResultSummary(result *mcps.ToolCallResult) string {
-	if result == nil {
-		return ""
-	}
-	lines := make([]string, 0, len(result.Content)+2)
-	if result.IsError {
-		lines = append(lines, "tool returned an error")
-	}
-	if result.StructuredContent != nil {
-		if data, err := json.Marshal(result.StructuredContent); err == nil {
-			lines = append(lines, string(data))
-		}
-	}
-	for _, item := range result.Content {
-		switch item.Type {
-		case "text":
-			if text := strings.TrimSpace(item.Text); text != "" {
-				lines = append(lines, text)
-			}
-		default:
-			if item.Data == nil {
-				continue
-			}
-			if data, err := json.Marshal(item.Data); err == nil {
-				lines = append(lines, string(data))
-			}
-		}
-	}
-	return strings.TrimSpace(strings.Join(lines, "\n"))
-}
-
 func BuildModelToolName(definition MCPToolDefinition) string {
 	if strings.TrimSpace(definition.ModelName) != "" {
 		return strings.TrimSpace(definition.ModelName)

internal/ai/runtime/internal/impl/adapter/tool_result_reducer.go

@@ -0,0 +1,75 @@
+package adapter
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"cs-agent/internal/ai/mcps"
+)
+
+const (
+	maxToolResultSummaryChars = 4000
+	maxToolResultSegments     = 12
+)
+
+// BuildReducedToolResultSummary returns a bounded text summary for MCP tool results.
+// It keeps the main payload visible to the model while preventing a single large tool
+// response from exhausting too much context.
+func BuildReducedToolResultSummary(result *mcps.ToolCallResult) string {
+	if result == nil {
+		return ""
+	}
+	segments := collectToolResultSegments(result)
+	if len(segments) == 0 {
+		return ""
+	}
+	text := strings.TrimSpace(strings.Join(segments, "\n"))
+	if text == "" {
+		return ""
+	}
+	runes := []rune(text)
+	if len(runes) <= maxToolResultSummaryChars {
+		return text
+	}
+	truncated := strings.TrimSpace(string(runes[:maxToolResultSummaryChars]))
+	return fmt.Sprintf("%s\n\n[tool result reduced: original_length=%d, kept_length=%d]", truncated, len(runes), maxToolResultSummaryChars)
+}
+
+func collectToolResultSegments(result *mcps.ToolCallResult) []string {
+	segments := make([]string, 0, len(result.Content)+2)
+	if result.IsError {
+		segments = append(segments, "tool returned an error")
+	}
+	if result.StructuredContent != nil {
+		if data, err := json.Marshal(result.StructuredContent); err == nil {
+			segments = appendNonBlankSegment(segments, string(data))
+		}
+	}
+	for _, item := range result.Content {
+		if len(segments) >= maxToolResultSegments {
+			segments = append(segments, "[tool result reduced: remaining segments omitted]")
+			break
+		}
+		switch item.Type {
+		case "text":
+			segments = appendNonBlankSegment(segments, item.Text)
+		default:
+			if item.Data == nil {
+				continue
+			}
+			if data, err := json.Marshal(item.Data); err == nil {
+				segments = appendNonBlankSegment(segments, string(data))
+			}
+		}
+	}
+	return segments
+}
+
+func appendNonBlankSegment(input []string, value string) []string {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return input
+	}
+	return append(input, value)
+}

internal/ai/runtime/tools/tool_search_tool.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"cs-agent/internal/ai/mcps"
+	impladapter "cs-agent/internal/ai/runtime/internal/impl/adapter"
 	"cs-agent/internal/ai/runtime/registry"
 	"cs-agent/internal/pkg/toolx"
 
@@ -282,32 +283,5 @@ func cloneArguments(input map[string]any) map[string]any {
 }
 
 func buildToolCallResultSummary(result *mcps.ToolCallResult) string {
-	if result == nil {
-		return ""
-	}
-	lines := make([]string, 0, len(result.Content)+2)
-	if result.IsError {
-		lines = append(lines, "tool returned an error")
-	}
-	if result.StructuredContent != nil {
-		if data, err := json.Marshal(result.StructuredContent); err == nil {
-			lines = append(lines, string(data))
-		}
-	}
-	for _, item := range result.Content {
-		switch item.Type {
-		case "text":
-			if text := strings.TrimSpace(item.Text); text != "" {
-				lines = append(lines, text)
-			}
-		default:
-			if item.Data == nil {
-				continue
-			}
-			if data, err := json.Marshal(item.Data); err == nil {
-				lines = append(lines, string(data))
-			}
-		}
-	}
-	return strings.TrimSpace(strings.Join(lines, "\n"))
+	return impladapter.BuildReducedToolResultSummary(result)
 }