Workflow published as MCP with File-List variable: tools/list inputSchema is missing the file-list parameter

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### Dify version

1.15.0

### Cloud or Self Hosted

Cloud

### Steps to reproduce

On Dify Cloud (online version), when a workflow that uses a File List (array[file]) input variable is published as an MCP server, calling tools/list returns an inputSchema that does not include the file-list parameter. Other input variables appear correctly in the schema; only the file-list variable is dropped.

1. Create a workflow with a File List (array[file]) input variable. here is my dsl

```yml
app:
description: ''
icon: 🤖
icon_background: '#FFEAD5'
icon_type: emoji
mode: workflow
name: extract_online_docx_file_content
use_icon_as_answer_icon: false
dependencies: []
kind: app
version: 0.6.0
workflow:
conversation_variables: []
environment_variables: []
features:
file_upload:
allowed_file_extensions:
- .JPG
- .JPEG
- .PNG
- .GIF
- .WEBP
- .SVG
allowed_file_types:
- image
allowed_file_upload_methods:
- local_file
- remote_url
enabled: false
fileUploadConfig:
attachment_image_file_size_limit: 2
audio_file_size_limit: 50
batch_count_limit: 5
file_size_limit: 15
file_upload_limit: 50
image_file_batch_limit: 10
image_file_size_limit: 10
single_chunk_attachment_limit: 10
video_file_size_limit: 100
workflow_file_upload_limit: 10
image:
enabled: false
number_limits: 3
transfer_methods:
- local_file
- remote_url
number_limits: 3
opening_statement: ''
retriever_resource:
enabled: true
sensitive_word_avoidance:
enabled: false
speech_to_text:
enabled: false
suggested_questions: []
suggested_questions_after_answer:
enabled: false
text_to_speech:
enabled: false
language: ''
voice: ''
graph:
edges:
- data:
isInIteration: false
isInLoop: false
sourceType: start
targetType: document-extractor
id: 1785288566414-source-1785288575867-target
source: '1785288566414'
sourceHandle: source
target: '1785288575867'
targetHandle: target
type: custom
zIndex: 0
- data:
isInIteration: false
isInLoop: false
sourceType: document-extractor
targetType: end
id: 1785288575867-source-1785288615044-target
source: '1785288575867'
sourceHandle: source
target: '1785288615044'
targetHandle: target
type: custom
zIndex: 0
nodes:
- data:
selected: true
title: 用户输入
type: start
variables:
- allowed_file_extensions: []
allowed_file_types:
- document
allowed_file_upload_methods:
- remote_url
default: ''
hide: false
hint: ''
label: file_url_array
max_length: 5
options: []
placeholder: ''
required: true
type: file-list
variable: file_url_array
height: 109
id: '1785288566414'
position:
x: 77
y: 261
positionAbsolute:
x: 77
y: 261
selected: true
sourcePosition: right
targetPosition: left
type: custom
width: 242
- data:
is_array_file: true
selected: false
title: 文档提取器
type: document-extractor
variable_selector:
- '1785288566414'
- file_url_array
height: 105
id: '1785288575867'
position:
x: 357
y: 282
positionAbsolute:
x: 357
y: 282
selected: false
sourcePosition: right
targetPosition: left
type: custom
width: 242
- data:
outputs:
- value_selector:
- '1785288575867'
- text
value_type: array[string]
variable: text
selected: false
title: 输出
type: end
height: 89
id: '1785288615044'
position:
x: 659
y: 282
positionAbsolute:
x: 659
y: 282
selected: false
sourcePosition: right
targetPosition: left
type: custom
width: 242
viewport:
x: 0
y: 60
zoom: 1
rag_pipeline_variables: []

```

2. Publish the workflow as an MCP server.

3. Connect an MCP client and call tools/list.

Inspect the returned inputSchema for the tool.

### ✔️ Expected Behavior

The file-list input variable should be present in the tool's inputSchema (or, if MCP file inputs are not supported, the limitation should be documented and surfaced clearly when publishing).

### ❌ Actual Behavior

The file-list parameter is missing from inputSchema, so MCP clients cannot pass files to the workflow.

Start at the MCP server publishing flow and the tools/list response that generates each tool's inputSchema. Reproduce the workflow with a File List (array[file]) variable, compare its schema with other input variables, and trace where the file-list parameter is omitted. Done means the parameter appears in inputSchema, or publishing clearly reports that MCP file inputs are unsupported.

Written by the indexing model from the issue text.