diff --git a/backend/internal/service/gateway_anthropic_apikey_passthrough_test.go b/backend/internal/service/gateway_anthropic_apikey_passthrough_test.go
index eba08a113b..2fb7c4baa3 100644
--- a/backend/internal/service/gateway_anthropic_apikey_passthrough_test.go
+++ b/backend/internal/service/gateway_anthropic_apikey_passthrough_test.go
@@ -769,6 +769,32 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_BuildRequestRejectsInvalidBas
 	require.Error(t, err)
 }
 
+func TestGatewayService_AnthropicAPIKeyPassthrough_StripsDeferredToolCacheControl(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
+	svc := &GatewayService{cfg: &config.Config{Security: config.SecurityConfig{URLAllowlist: config.URLAllowlistConfig{Enabled: false}}}}
+	account := &Account{Platform: PlatformAnthropic, Type: AccountTypeAPIKey}
+	body := []byte(`{"tools":[{"name":"deferred","custom":{"defer_loading":true},"cache_control":{"type":"ephemeral"}},{"name":"top-level-deferred","defer_loading":true,"cache_control":{"type":"ephemeral"}},{"name":"ordinary","defer_loading":false,"cache_control":{"type":"ephemeral"}},{"name":"malformed","defer_loading":"true","cache_control":{"type":"ephemeral"}}]}`)
+
+	_, wireBody, err := svc.buildUpstreamRequestAnthropicAPIKeyPassthrough(context.Background(), c, account, body, "k")
+	require.NoError(t, err)
+	require.False(t, gjson.GetBytes(wireBody, "tools.0.cache_control").Exists())
+	require.False(t, gjson.GetBytes(wireBody, "tools.1.cache_control").Exists())
+	require.True(t, gjson.GetBytes(wireBody, "tools.2.cache_control").Exists())
+	require.True(t, gjson.GetBytes(wireBody, "tools.3.cache_control").Exists())
+
+	countReq, err := svc.buildCountTokensRequestAnthropicAPIKeyPassthrough(context.Background(), c, account, body, "k")
+	require.NoError(t, err)
+	countBody, err := io.ReadAll(countReq.Body)
+	require.NoError(t, err)
+	require.False(t, gjson.GetBytes(countBody, "tools.0.cache_control").Exists())
+	require.False(t, gjson.GetBytes(countBody, "tools.1.cache_control").Exists())
+	require.True(t, gjson.GetBytes(countBody, "tools.2.cache_control").Exists())
+	require.True(t, gjson.GetBytes(countBody, "tools.3.cache_control").Exists())
+}
+
 func TestGatewayService_AnthropicOAuth_NotAffectedByAPIKeyPassthroughToggle(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	rec := httptest.NewRecorder()
diff --git a/backend/internal/service/gateway_anthropic_passthrough.go b/backend/internal/service/gateway_anthropic_passthrough.go
index def4d34648..533e780017 100644
--- a/backend/internal/service/gateway_anthropic_passthrough.go
+++ b/backend/internal/service/gateway_anthropic_passthrough.go
@@ -310,6 +310,7 @@ func (s *GatewayService) buildUpstreamRequestAnthropicAPIKeyPassthrough(
 	body []byte,
 	token string,
 ) (*http.Request, []byte, error) {
+	body = stripDeferredToolCacheControl(body)
 	targetURL := claudeAPIURL
 	baseURL := account.GetBaseURL()
 	if baseURL != "" {
diff --git a/backend/internal/service/gateway_context_management_test.go b/backend/internal/service/gateway_context_management_test.go
index bdeb2c600b..b7ab3e9429 100644
--- a/backend/internal/service/gateway_context_management_test.go
+++ b/backend/internal/service/gateway_context_management_test.go
@@ -4,6 +4,7 @@ package service
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -650,6 +651,51 @@ func TestBuildCountTokensRequest_APIKeyHaiku_StripsContextManagementEndToEnd(t *
 		"count_tokens API-key + 客户端未带 beta token → body strip")
 }
 
+func TestBuildCountTokensRequest_StripsCacheControlOnlyFromLiteralDeferredTools(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	body := []byte(`{"model":"claude-haiku-4-5","messages":[],"tools":[{"name":"deferred","custom":{"defer_loading":true},"cache_control":{"type":"ephemeral"}},{"name":"ordinary","custom":{"defer_loading":false},"cache_control":{"type":"ephemeral"}},{"name":"string","custom":{"defer_loading":"true"},"cache_control":{"type":"ephemeral"}},{"name":"number","custom":{"defer_loading":1},"cache_control":{"type":"ephemeral"}},{"name":"object","custom":{"defer_loading":{}},"cache_control":{"type":"ephemeral"}}]}`)
+
+	tests := []struct {
+		name      string
+		account   *Account
+		token     string
+		tokenType string
+	}{
+		{
+			name:      "generic API key",
+			account:   &Account{Platform: PlatformAnthropic, Type: AccountTypeAPIKey},
+			token:     "sk-ant-test",
+			tokenType: "apikey",
+		},
+		{
+			name:      "recognized Claude Code OAuth without mimicry",
+			account:   &Account{Platform: PlatformAnthropic, Type: AccountTypeOAuth},
+			token:     "oauth-token",
+			tokenType: "oauth",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			rec := httptest.NewRecorder()
+			c, _ := gin.CreateTestContext(rec)
+			c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages/count_tokens", nil)
+			svc := &GatewayService{cfg: &config.Config{}}
+
+			req, wireBody, err := svc.buildCountTokensRequest(
+				context.Background(), c, tt.account, body,
+				tt.token, tt.tokenType, "claude-haiku-4-5", false,
+			)
+			require.NoError(t, err)
+			require.False(t, gjson.GetBytes(wireBody, "tools.0.cache_control").Exists())
+			for idx := 1; idx < 5; idx++ {
+				require.Equal(t, "ephemeral", gjson.GetBytes(wireBody, fmt.Sprintf("tools.%d.cache_control.type", idx)).String())
+			}
+			require.JSONEq(t, string(wireBody), string(readUpstreamBodyForTest(t, req)))
+		})
+	}
+}
+
 // count_tokens passthrough preserve 测试
 func TestBuildCountTokensRequestAnthropicAPIKeyPassthrough_PreservesContextManagementWhenClientHeaderHasBeta(t *testing.T) {
 	gin.SetMode(gin.TestMode)
diff --git a/backend/internal/service/gateway_count_tokens.go b/backend/internal/service/gateway_count_tokens.go
index 7b66ac9596..003cbb7c1e 100644
--- a/backend/internal/service/gateway_count_tokens.go
+++ b/backend/internal/service/gateway_count_tokens.go
@@ -366,6 +366,7 @@ func (s *GatewayService) buildCountTokensRequestAnthropicAPIKeyPassthrough(
 	body []byte,
 	token string,
 ) (*http.Request, error) {
+	body = stripDeferredToolCacheControl(body)
 	targetURL := claudeAPICountTokensURL
 	baseURL := account.GetBaseURL()
 	if baseURL != "" {
@@ -429,6 +430,7 @@ func (s *GatewayService) buildCountTokensRequestAnthropicAPIKeyPassthrough(
 
 // buildCountTokensRequest 构建 count_tokens 上游请求
 func (s *GatewayService) buildCountTokensRequest(ctx context.Context, c *gin.Context, account *Account, body []byte, token, tokenType, modelID string, mimicClaudeCode bool) (*http.Request, []byte, error) {
+	body = stripDeferredToolCacheControl(body)
 	// 确定目标 URL
 	targetURL := claudeAPICountTokensURL
 	if account.Type == AccountTypeAPIKey {
diff --git a/backend/internal/service/gateway_tool_rewrite.go b/backend/internal/service/gateway_tool_rewrite.go
index da62daf961..d1b6993723 100644
--- a/backend/internal/service/gateway_tool_rewrite.go
+++ b/backend/internal/service/gateway_tool_rewrite.go
@@ -248,14 +248,18 @@ func applyToolNameRewriteToBody(body []byte, rw *ToolNameRewrite) []byte {
 	return body
 }
 
-// applyToolsLastCacheBreakpoint 在 tools 数组最后一个工具上注入 cache_control
-// 断点，对齐 Parrot `tools[-1]["cache_control"] = {"type":"ephemeral","ttl":"1h"}`
-// 行为，但 ttl 按本仓规则：
+// applyToolsLastCacheBreakpoint 在最后一个非延迟加载工具上注入 cache_control
+// 断点。Anthropic 不允许 defer_loading=true 的工具携带 cache_control，
+// 因此会先清理所有延迟加载工具上的客户端断点。兼容官方顶层字段和
+// Claude Code 使用的 custom.defer_loading 字段。其余行为对齐 Parrot
+// `tools[-1]["cache_control"] = {"type":"ephemeral","ttl":"1h"}`，
+// 但 ttl 按本仓规则：
 //   - 客户端已为该 tool 显式设置 cache_control.ttl → 完全透传不覆盖
 //   - 否则注入 {"type":"ephemeral","ttl": claude.DefaultCacheControlTTL}
 //
 // 纯副作用函数，tools 不存在或为空数组时 no-op。
 func applyToolsLastCacheBreakpoint(body []byte) []byte {
+	body = stripDeferredToolCacheControl(body)
 	tools := gjson.GetBytes(body, "tools")
 	if !tools.IsArray() {
 		return body
@@ -264,7 +268,17 @@ func applyToolsLastCacheBreakpoint(body []byte) []byte {
 	if len(arr) == 0 {
 		return body
 	}
-	lastIdx := len(arr) - 1
+	lastIdx := -1
+	for idx, tool := range arr {
+		if isDeferredLoadingTool(tool) {
+			continue
+		}
+		lastIdx = idx
+	}
+	if lastIdx == -1 {
+		return body
+	}
+
 	existingCC := arr[lastIdx].Get("cache_control")
 
 	if existingCC.Exists() && existingCC.Get("ttl").String() != "" {
@@ -285,6 +299,29 @@ func applyToolsLastCacheBreakpoint(body []byte) []byte {
 	return body
 }
 
+func isDeferredLoadingTool(tool gjson.Result) bool {
+	return tool.Get("defer_loading").Type == gjson.True ||
+		tool.Get("custom.defer_loading").Type == gjson.True
+}
+
+// stripDeferredToolCacheControl removes the cache marker Anthropic rejects on
+// deferred tools. Only the literal JSON boolean true enables deferred loading.
+func stripDeferredToolCacheControl(body []byte) []byte {
+	tools := gjson.GetBytes(body, "tools")
+	if !tools.IsArray() {
+		return body
+	}
+	for idx, tool := range tools.Array() {
+		if !isDeferredLoadingTool(tool) || !tool.Get("cache_control").Exists() {
+			continue
+		}
+		if next, err := sjson.DeleteBytes(body, fmt.Sprintf("tools.%d.cache_control", idx)); err == nil {
+			body = next
+		}
+	}
+	return body
+}
+
 // restoreToolNamesInBytes 对 bytes chunk 做逆向还原：假名 → 真名。
 // 按 ReverseOrdered 的假名长度倒序逐个 bytes.Replace，防止子串冲突
 // （与 Parrot _restore_tool_names_in_chunk 的 sorted(..., reverse=True) 等价）。
diff --git a/backend/internal/service/gateway_tool_rewrite_test.go b/backend/internal/service/gateway_tool_rewrite_test.go
index 9e6f6806da..c894ef708c 100644
--- a/backend/internal/service/gateway_tool_rewrite_test.go
+++ b/backend/internal/service/gateway_tool_rewrite_test.go
@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"fmt"
 	"strings"
 	"testing"
 
@@ -149,6 +150,34 @@ func TestApplyToolsLastCacheBreakpoint_PassesThroughClientTTL(t *testing.T) {
 	require.Equal(t, "1h", gjson.GetBytes(out, "tools.0.cache_control.ttl").String())
 }
 
+func TestApplyToolsLastCacheBreakpoint_StripsDeferredToolCacheControl(t *testing.T) {
+	body := []byte(`{"tools":[{"name":"a","custom":{"defer_loading":true},"cache_control":{"type":"ephemeral","ttl":"1h"}},{"name":"b","custom":{"defer_loading":true}}]}`)
+	out := applyToolsLastCacheBreakpoint(body)
+
+	require.False(t, gjson.GetBytes(out, "tools.0.cache_control").Exists())
+	require.False(t, gjson.GetBytes(out, "tools.1.cache_control").Exists())
+}
+
+func TestApplyToolsLastCacheBreakpoint_SkipsDeferredFinalTool(t *testing.T) {
+	body := []byte(`{"tools":[{"name":"a","input_schema":{}},{"name":"b","defer_loading":true}]}`)
+	out := applyToolsLastCacheBreakpoint(body)
+
+	require.Equal(t, "ephemeral", gjson.GetBytes(out, "tools.0.cache_control.type").String())
+	require.Equal(t, "5m", gjson.GetBytes(out, "tools.0.cache_control.ttl").String())
+	require.False(t, gjson.GetBytes(out, "tools.1.cache_control").Exists())
+}
+
+func TestApplyToolsLastCacheBreakpoint_OnlyLiteralTrueIsDeferred(t *testing.T) {
+	body := []byte(`{"tools":[{"name":"custom-true","custom":{"defer_loading":true},"cache_control":{"type":"ephemeral"}},{"name":"top-level-true","defer_loading":true,"cache_control":{"type":"ephemeral"}},{"name":"false","defer_loading":false,"cache_control":{"type":"ephemeral"}},{"name":"string","defer_loading":"true","cache_control":{"type":"ephemeral"}},{"name":"number","defer_loading":1,"cache_control":{"type":"ephemeral"}},{"name":"object","defer_loading":{},"cache_control":{"type":"ephemeral"}}]}`)
+	out := stripDeferredToolCacheControl(body)
+
+	require.False(t, gjson.GetBytes(out, "tools.0.cache_control").Exists())
+	require.False(t, gjson.GetBytes(out, "tools.1.cache_control").Exists())
+	for idx := 2; idx < 6; idx++ {
+		require.Equal(t, "ephemeral", gjson.GetBytes(out, fmt.Sprintf("tools.%d.cache_control.type", idx)).String())
+	}
+}
+
 func TestStripMessageCacheControl(t *testing.T) {
 	body := []byte(`{"messages":[{"role":"user","content":[{"type":"text","text":"hi","cache_control":{"type":"ephemeral"}}]}]}`)
 	out := stripMessageCacheControl(body)
diff --git a/backend/internal/service/gateway_upstream_request.go b/backend/internal/service/gateway_upstream_request.go
index c5d962f20b..0a8efbdd5e 100644
--- a/backend/internal/service/gateway_upstream_request.go
+++ b/backend/internal/service/gateway_upstream_request.go
@@ -19,6 +19,7 @@ import (
 )
 
 func (s *GatewayService) buildUpstreamRequest(ctx context.Context, c *gin.Context, account *Account, body []byte, token, tokenType, modelID string, reqStream bool, mimicClaudeCode bool) (*http.Request, []byte, error) {
+	body = stripDeferredToolCacheControl(body)
 	if account.Platform == PlatformAnthropic && account.Type == AccountTypeServiceAccount {
 		req, err := s.buildUpstreamRequestAnthropicVertex(ctx, c, account, body, token, modelID, reqStream)
 		return req, body, err