diff --git a/services/pascal-editor/apps/editor/app/api/agent/chat/route.ts b/services/pascal-editor/apps/editor/app/api/agent/chat/route.ts
index 597ced10d..8d3dfe525 100644
--- a/services/pascal-editor/apps/editor/app/api/agent/chat/route.ts
+++ b/services/pascal-editor/apps/editor/app/api/agent/chat/route.ts
@@ -256,6 +256,7 @@ export async function POST(request: Request) {
                 hasMutation: session.hasMutation(),
                 mutationRequired,
                 mutationToolNames: session.mutationToolNames,
+                readOnlyToolNames: session.readOnlyToolNames,
                 stepNumber,
               }),
           }),
diff --git a/services/pascal-editor/apps/editor/lib/pascal-agent-intent.test.ts b/services/pascal-editor/apps/editor/lib/pascal-agent-intent.test.ts
index cdf722d2c..f3fe11e0b 100644
--- a/services/pascal-editor/apps/editor/lib/pascal-agent-intent.test.ts
+++ b/services/pascal-editor/apps/editor/lib/pascal-agent-intent.test.ts
@@ -24,6 +24,42 @@ describe('Pascal agent intent', () => {
     ).toBe(false)
   })
 
+  test('does not treat a negated mutation as permission to write', () => {
+    expect(
+      requiresPascalMutation([
+        {
+          role: 'user',
+          parts: [
+            {
+              type: 'text',
+              text: '请只读取当前场景并汇总元素数量，不要修改任何模型。',
+            },
+          ],
+        },
+      ]),
+    ).toBe(false)
+
+    expect(
+      requiresPascalMutation([
+        {
+          role: 'user',
+          parts: [{ type: 'text', text: 'Inspect this scene, but do not modify the model.' }],
+        },
+      ]),
+    ).toBe(false)
+  })
+
+  test('keeps other requested mutations after removing a negated action', () => {
+    expect(
+      requiresPascalMutation([
+        {
+          role: 'user',
+          parts: [{ type: 'text', text: '不要删除现有墙体，只添加一扇窗。' }],
+        },
+      ]),
+    ).toBe(true)
+  })
+
   test('uses the latest user message', () => {
     expect(
       requiresPascalMutation([
@@ -40,6 +76,7 @@ describe('Pascal agent intent', () => {
         hasMutation: false,
         mutationRequired: true,
         mutationToolNames: ['create_room', 'add_door'],
+        readOnlyToolNames: ['read_scene'],
         stepNumber: 1,
       }),
     ).toEqual({
@@ -54,8 +91,24 @@ describe('Pascal agent intent', () => {
         hasMutation: true,
         mutationRequired: true,
         mutationToolNames: ['create_room'],
+        readOnlyToolNames: ['read_scene'],
         stepNumber: 3,
       }),
     ).toEqual({ toolChoice: 'auto' })
   })
+
+  test('only exposes inspection tools for read-only requests', () => {
+    expect(
+      pascalAgentStepPolicy({
+        hasMutation: false,
+        mutationRequired: false,
+        mutationToolNames: ['apply_patch', 'save_scene'],
+        readOnlyToolNames: ['read_scene', 'list_levels'],
+        stepNumber: 0,
+      }),
+    ).toEqual({
+      activeTools: ['read_scene', 'list_levels'],
+      toolChoice: 'auto',
+    })
+  })
 })
diff --git a/services/pascal-editor/apps/editor/lib/pascal-agent-intent.ts b/services/pascal-editor/apps/editor/lib/pascal-agent-intent.ts
index 33b96dc3c..817d093ae 100644
--- a/services/pascal-editor/apps/editor/lib/pascal-agent-intent.ts
+++ b/services/pascal-editor/apps/editor/lib/pascal-agent-intent.ts
@@ -1,5 +1,25 @@
-const MUTATION_INTENT =
-  /(?:设计|创建|生成|添加|增加|新增|修改|调整|编辑|删除|移动|旋转|缩放|布置|装修|建造|搭建|修复|design|create|generate|add|modify|update|edit|delete|remove|move|rotate|scale|furnish|build|repair|fix)/i
+const CHINESE_MUTATION_ACTIONS =
+  '设计|创建|生成|添加|增加|新增|修改|调整|编辑|删除|移动|旋转|缩放|布置|装修|建造|搭建|修复'
+const ENGLISH_MUTATION_ACTIONS =
+  'design|create|generate|add|modify|change|update|edit|delete|remove|move|rotate|scale|furnish|build|repair|fix'
+
+const MUTATION_INTENT = new RegExp(
+  `(?:${CHINESE_MUTATION_ACTIONS}|${ENGLISH_MUTATION_ACTIONS})`,
+  'i',
+)
+
+const NEGATED_CHINESE_MUTATION = new RegExp(
+  `(?:不要|请勿|勿|无需|不需要|不用|禁止|避免|不(?:再)?)[^，。；;,.!?！？]{0,32}(?:${CHINESE_MUTATION_ACTIONS})`,
+  'gi',
+)
+const NEGATED_ENGLISH_MUTATION = new RegExp(
+  `(?:do\\s+not|don't|dont|please\\s+do\\s+not|please\\s+don't|without|avoid)\\s+[^,.!?;]{0,48}(?:${ENGLISH_MUTATION_ACTIONS})`,
+  'gi',
+)
+
+function actionableIntentText(text: string): string {
+  return text.replace(NEGATED_CHINESE_MUTATION, ' ').replace(NEGATED_ENGLISH_MUTATION, ' ')
+}
 
 export function requiresPascalMutation(messages: unknown[]): boolean {
   const latestUserMessage = [...messages]
@@ -24,15 +44,19 @@ export function requiresPascalMutation(messages: unknown[]): boolean {
     .map((part) => part.text)
     .join(' ')
 
-  return MUTATION_INTENT.test(text)
+  return MUTATION_INTENT.test(actionableIntentText(text))
 }
 
 export function pascalAgentStepPolicy(params: {
   hasMutation: boolean
   mutationRequired: boolean
   mutationToolNames: string[]
+  readOnlyToolNames: string[]
   stepNumber: number
 }): { activeTools?: string[]; toolChoice: 'auto' | 'required' } {
+  if (!params.mutationRequired) {
+    return { activeTools: params.readOnlyToolNames, toolChoice: 'auto' }
+  }
   if (!(params.mutationRequired && !params.hasMutation)) return { toolChoice: 'auto' }
   if (params.stepNumber < 1) return { toolChoice: 'required' }
   return {
diff --git a/services/pascal-editor/apps/editor/lib/pascal-agent-mcp.ts b/services/pascal-editor/apps/editor/lib/pascal-agent-mcp.ts
index 7d7b47b71..efa768511 100644
--- a/services/pascal-editor/apps/editor/lib/pascal-agent-mcp.ts
+++ b/services/pascal-editor/apps/editor/lib/pascal-agent-mcp.ts
@@ -45,6 +45,7 @@ export interface PascalAgentMcpSession {
   close: () => Promise<void>
   hasMutation: () => boolean
   mutationToolNames: string[]
+  readOnlyToolNames: string[]
   saveDraft: (abortSignal?: AbortSignal) => Promise<void>
   sceneName: string
   tools: ToolSet
@@ -117,6 +118,10 @@ export function isPascalAgentMutationTool(name: string): boolean {
   return MUTATION_TOOL_NAMES.has(name)
 }
 
+function isPascalAgentWriteTool(name: string): boolean {
+  return name === 'save_scene' || isPascalAgentMutationTool(name)
+}
+
 function readSceneName(result: unknown, fallback: string): string {
   const structured = (result as { structuredContent?: { name?: unknown } })?.structuredContent
   return typeof structured?.name === 'string' && structured.name.trim()
@@ -228,10 +233,12 @@ export async function createPascalAgentMcpSession(params: {
       await client?.close()
     }
 
+    const toolNames = Object.keys(tools)
     return {
       close,
       hasMutation: () => mutationCount > 0,
-      mutationToolNames: Object.keys(tools).filter(isPascalAgentMutationTool),
+      mutationToolNames: toolNames.filter(isPascalAgentMutationTool),
+      readOnlyToolNames: toolNames.filter((name) => !isPascalAgentWriteTool(name)),
       sceneName,
       tools,
       saveDraft: async (abortSignal) => {