fix: sanitize private tool schema fields (#7207)

packages/service/core/ai/llm/request/requestBody.ts

-import type { ChatCompletionCreateParams } from '@fastgpt/global/core/ai/llm/type';
+import type {
+  ChatCompletionCreateParams,
+  ChatCompletionTool
+} from '@fastgpt/global/core/ai/llm/type';
 import { getLLMSupportParams } from '@fastgpt/global/core/ai/llm/utils';
 import json5 from 'json5';
 import { computedMaxToken, computedTemperature } from '../../utils';
@@ -6,6 +9,38 @@ import { getLLMModel } from '../../model';
 import type { InferCompletionsBody, LLMRequestBodyType } from './types';
 import type { LLMModelItemType } from '@fastgpt/global/core/ai/model.schema';
 
+const privateToolSchemaKeys = new Set(['toolDescription', 'x-tool-description', 'isSecret']);
+
+/**
+ * 清理 FastGPT 内部工具参数扩展字段，避免 OpenAI-compatible SDK 转成 Gemini 等原生
+ * function declaration 时，把 toolDescription 这类非供应商 schema 字段透传出去。
+ */
+const sanitizeToolParametersSchema = (schema: unknown): unknown => {
+  if (Array.isArray(schema)) {
+    return schema.map(sanitizeToolParametersSchema);
+  }
+  if (!schema || typeof schema !== 'object') {
+    return schema;
+  }
+
+  return Object.fromEntries(
+    Object.entries(schema as Record<string, unknown>)
+      .filter(([key]) => !privateToolSchemaKeys.has(key))
+      .map(([key, value]) => [key, sanitizeToolParametersSchema(value)])
+  );
+};
+
+const sanitizeCompletionTools = (tools?: ChatCompletionTool[]): ChatCompletionTool[] | undefined =>
+  tools?.map((tool) => ({
+    ...tool,
+    function: {
+      ...tool.function,
+      parameters: sanitizeToolParametersSchema(
+        tool.function.parameters
+      ) as ChatCompletionTool['function']['parameters']
+    }
+  }));
+
 /**
  * 把 FastGPT 内部 LLM body 转成 OpenAI SDK 可请求的 completions body。
  *
@@ -22,6 +57,7 @@ export const llmCompletionsBodyFormat = async <T extends ChatCompletionCreatePar
   modelData: LLMModelItemType;
 }> => {
   const { tools, tool_choice, parallel_tool_calls, toolCallMode, ...body } = input;
+  const sanitizedTools = sanitizeCompletionTools(tools);
   // 这些字段只影响 FastGPT 自身逻辑，不能透传给模型供应商。
   delete body.retainDatasetCite;
   delete body.useVision;
@@ -82,8 +118,8 @@ export const llmCompletionsBodyFormat = async <T extends ChatCompletionCreatePar
     stop: formatStop?.length ? formatStop : undefined,
     // prompt tool 模式通过 prompt 描述工具，直接传 tools 会让部分模型同时触发两套协议。
     ...(toolCallMode === 'toolChoice' &&
-      tools?.length && {
-        tools,
+      sanitizedTools?.length && {
+        tools: sanitizedTools,
         tool_choice,
         parallel_tool_calls
       })

packages/service/test/core/ai/llm/request/requestBody.test.ts

@@ -151,6 +151,81 @@ describe('llmCompletionsBodyFormat', () => {
     expect(requestBody).not.toHaveProperty('tools');
   });
 
+  it('should remove FastGPT private tool schema fields before sending tools to model', async () => {
+    mockGetLLMModel.mockReturnValue(createModel());
+
+    const { requestBody } = await llmCompletionsBodyFormat({
+      model: 'gpt-4o',
+      messages,
+      stream: false,
+      tools: [
+        {
+          type: 'function',
+          function: {
+            name: 'search',
+            description: 'search',
+            parameters: {
+              type: 'object',
+              properties: {
+                query: {
+                  type: 'string',
+                  description: 'Search query',
+                  toolDescription: 'Query for model',
+                  'x-tool-description': 'HTTP query',
+                  isSecret: true
+                },
+                filters: {
+                  type: 'array',
+                  items: {
+                    type: 'object',
+                    properties: {
+                      key: {
+                        type: 'string',
+                        toolDescription: 'Filter key'
+                      }
+                    },
+                    toolDescription: 'Filter object'
+                  }
+                }
+              }
+            }
+          }
+        }
+      ],
+      toolCallMode: 'toolChoice'
+    });
+
+    expect(requestBody.tools).toEqual([
+      {
+        type: 'function',
+        function: {
+          name: 'search',
+          description: 'search',
+          parameters: {
+            type: 'object',
+            properties: {
+              query: {
+                type: 'string',
+                description: 'Search query'
+              },
+              filters: {
+                type: 'array',
+                items: {
+                  type: 'object',
+                  properties: {
+                    key: {
+                      type: 'string'
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    ]);
+  });
+
   it('should apply field map after base formatting', async () => {
     mockGetLLMModel.mockReturnValue(
       createModel({