[FEATURE] Slack MCP integration: support downloading file attachments from messages

Problem Statement

When using the Slack MCP connector to read messages and threads, file attachments (PDFs, images, documents) referenced in messages are visible in the message metadata but cannot be downloaded or accessed. This makes it impossible to process attached files — for example, reading a candidate's PDF resume shared in a Slack thread.

Currently the only workaround is to ask the user to manually download the file and provide a local path, which breaks the workflow and defeats the purpose of the Slack integration.

Proposed Solution

Add a tool to the Slack MCP connector (e.g. slack_download_file) that can download file attachments from Slack messages by file ID or URL, saving them to a temporary local path so they can be read and processed by Claude.

Alternative Solutions

• Manually downloading the file and providing the local path — works but breaks the conversational flow
• Using the Slack API directly via curl in Bash — requires a Slack token which the user may not have readily available

Priority

Medium - Would be very helpful

Feature Category

MCP server integration

Use Case Example

1. A recruiter shares a candidate's PDF resume in a Slack thread
2. I ask Claude to read the thread and evaluate the candidate
3. Claude reads the thread via slack_read_thread and sees Files: Resume.pdf in the message
4. Claude should be able to download and read that PDF to complete the evaluation
5. Currently this fails — Claude can see the filename but cannot access the file content