Get started changedclaude-tag/users/getting-started
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### Files you attach
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7878After you've handed Claude a task, the first question is what it has to work with. The short version: it reads the thread you tagged it in, it can search your workspace's public channels, and anything beyond Slack depends on what your admin connected.
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80| What you give Claude | Can Claude read it? |
81| :----------------------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
82| Messages in this thread | Yes. Mentioning it mid-thread also gives it the thread's earlier messages |
83| An image or screenshot you attach | Yes |
84| Other public channels in your workspace | By searching only, the same way a person searches Slack; Claude can find a message by keyword but can't read a channel's full history unless it's been added there |
85| Private channels and DMs | Only from inside them. Adding Claude to a private channel lets it work there, but the channel stays unreadable from any other channel or DM. |
86| A link you paste, like a Google Doc or a webpage | Only if your admin allowed that site for this channel. If not, Claude tells you it can't reach it. For files in your personal Drive or Google account, DM Claude instead; [a DM uses your own connectors](/docs/claude-tag/concepts/agent-identity#direct-message-channels) |
87| A Slack canvas | No |
88| A message you edited after sending | Yes. Each edit sends Claude a note showing the text before and after the edit. Claude reads the note but doesn't act on it, so say a correction in a new reply. Deleting a message doesn't notify Claude |
80| What you give Claude | Can Claude read it? |
81| :---------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
82| Messages in this thread | Yes. Mentioning it mid-thread also gives it the thread's earlier messages |
83| A file you attach (image, screenshot, PDF, or another type) | Yes, up to a size limit that depends on the file type. See [Files you attach](#files-you-attach) |
84| Other public channels in your workspace | By searching only, the same way a person searches Slack; Claude can find a message by keyword but can't read a channel's full history unless it's been added there |
85| Private channels and DMs | Only from inside them. Adding Claude to a private channel lets it work there, but the channel stays unreadable from any other channel or DM. |
86| A link you paste, like a Google Doc or a webpage | Only if your admin allowed that site for this channel. If not, Claude tells you it can't reach it. For files in your personal Drive or Google account, DM Claude instead; [a DM uses your own connectors](/docs/claude-tag/concepts/agent-identity#direct-message-channels) |
87| A Slack canvas | No |
88| A message you edited after sending | Yes. Each edit sends Claude a note showing the text before and after the edit. Claude reads the note but doesn't act on it, so say a correction in a new reply. Deleting a message doesn't notify Claude |
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9090The fastest way to find out for your channel is to ask: `@Claude can you read the doc I just linked?` gets you a yes or a "that site isn't allowed here."
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92### Files you attach
93
94Claude reads images and PDFs directly. It puts any other file type in its working files and opens it from there when the task needs it. Claude accepts files within these limits.
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96* **Images**: up to about 3.75 MB each
97* **PDFs**: up to 5 MB each
98* **Other files** (spreadsheets, code, archives, documents): up to 100 MB each
99* **Number of files**: up to 5 per message. Claude ignores any beyond the fifth.
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101Claude can't read an image or PDF over its limit and answers from the rest of your message. To hand Claude a larger image or PDF, resize the image, split the PDF, or paste the text.
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92103<Note>Slack doesn't expose personal account settings (your sidebar, notification preferences, channel membership, or DMs between you and other people) to apps. If you want help organizing channels, paste or screenshot the list and Claude can propose a scheme you apply yourself.</Note>
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