Claude pdf-viewer connectorRead, annotate and fill in your PDFs in Claude Desktop.
The Claude pdf-viewer connector exposes 9 tools. 3 read PDFs, 2 can annotate or save a file, 4 are documented nowhere. Below: what Claude does with your documents in Claude Desktop, what it can overwrite, and what stays in the dark.
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What changes if you live in PDFs all day
pdf-viewer is an extension published by Anthropic that installs in Claude Desktop. It opens your PDFs in an interactive viewer right in the conversation and keeps Claude posted on the page you're looking at. So you can ask it to explain a passage, highlight a heading or fill in a field without switching to another app.
Track down the right file. list_pdfs lists the local files and sources available, then display_pdf opens the one you want in the viewer.
Annotate and fill in a form. With interact, Claude navigates, searches, extracts pages, adds highlights, notes or stamps, fills in fields and saves the result to a file. The guide lists the annotation types it supports: highlight, underline, strikethrough, note, rectangle, circle, line, free text, stamp and image.
Let the viewer do its part. read_pdf_bytes and save_pdf are reserved for the viewer itself: one loads the file in chunks, the other writes the annotated PDF back to disk.
What Claude doesn't do here: it doesn't work on the web or on mobile, since this is a Claude Desktop extension. Four of the tools on the sheet aren't described by any source. And nothing runs on its own between your messages. Running the same work over a pile of PDFs unattended calls for an automation tool; the Integrations hub covers that side.
The vocabulary in one minute
Five words that come up below.
- Connector
- What you install once to open a tool or service to Claude; here, an extension that runs on your own computer.
- Tool
- A named action the connector lends Claude. It picks which ones to call on its own, and the directory lists them by name.
- Desktop extension
- A connector installed in the Claude Desktop app, working on the machine itself rather than on an online service.
- Approval
- The confirmation Claude waits for before an action that changes something, shown in the chat right when it matters.
- MCP
- The open standard linking connectors to Claude; it's what lets the assistant drive an outside tool at all.
Install pdf-viewer in Claude in three steps
- 01
Open Claude Desktop
This extension only lives in the Claude Desktop app. Open its settings, then Customize and Connectors, and find pdf-viewer. On Team or Enterprise, an Owner or Primary Owner has to enable it first.
- 02
Add it
Click Connect on its row. No account sign-in is described for this extension, which works on your local files. If something goes wrong, use Disconnect and start over.
- 03
Stay in control of access
If an authorization screen ever shows up for a service, read it before accepting: that screen, not Claude, sets how far access goes. Here, what matters most is which folders the extension can reach.
The 9 tools, grouped by what they do
pdf-viewer gives Claude 9 tools: 3 that read your account, 2 that change something in it, and 4 no official source describes.
Three groups: what Claude reads, what can change a file, and what no source describes. Names stay in English.
- 3 read
- 2 write
- 4 not documented
What Claude reads (3)
3 toolsThree tools that list, display or load a PDF without changing it.
list_pdfs
Builds the list of local PDF files and origins the extension can open, so the right document can be picked before anything is displayed.
display_pdf
Opens the document in the interactive viewer, inside the chat, with search, navigation and text extraction. From then on, the viewer tells Claude which page is showing.
read_pdf_bytes
Reserved for the viewer, not for Claude: according to the publisher's guide, it streams the PDF's data in chunks to the app. There's nothing to ask it directly.
What can change a file (2)
2 toolsTwo tools that annotate or rewrite a PDF. No source describes their confirmation, so the general rule below applies.
interact
Approval: see the ruleDrives the open document: navigation, search, page extraction, highlights, notes, stamps, form filling and saving to a file. This is the tool that can actually change your PDF.
save_pdf
Approval: see the ruleOnly the viewer calls this one: it writes the annotated PDF back to your disk. The publisher's guide says the model saves through interact, not through this tool.
Undocumented (4)
4 toolsThe sheet publishes these four names and nothing else. No official text says what they do, and we won't guess from a name.
poll_pdf_commands
This name shows up on the sheet's list without a single line of explanation. The publisher's guide doesn't mention it and no Claude page covers it, so this page stops there.
submit_page_data
Same silence here: no official source describes it, and the directory sheet publishes the name and nothing more. Rather than read meaning into that name, we flag the gap as it stands.
submit_save_data
No official documentation, from Anthropic or in the example's guide, describes this tool. All we know is that it appears on the extension's sheet.
submit_viewer_state
The fourth name on the list without a single sentence from a source. This page assigns it no function, since nothing published allows saying more.
What Claude asks before acting
By default, Claude stops and asks for your go-ahead before every action it takes for you on an account or service. The request appears in the chat, at the moment it matters.
For this extension, no source describes a confirmation specific to interact or save_pdf, the two tools that can change a file. The publisher's guide adds two file-side safeguards: a save fails if the file already exists unless overwrite is requested, and the path has to sit under a folder opened to the extension. On Team and Enterprise, Owners decide whether a member may let some actions through without a fresh prompt, and can restrict the connector for the whole organization.
Which plans it's available on
None of the 819 sheets in the official directory shows plan availability. Per connector, that information isn't published anywhere.
The general rule is published: desktop extensions install in Claude Desktop, and remote connectors are open on Claude, Cowork, Claude Desktop and mobile. On Team and Enterprise, an Owner or Primary Owner enables them for the organization before members use them. The current state shows on the pdf-viewer sheet in the official directory.
Where this connector stops
A connector isn't an automation. Claude calls these tools while it answers you, so no PDF opens or gets annotated by itself.
The tool list is an observed floor, not a ceiling: an admin can open actions that appear on no public sheet. This connector is documented only by the guide of the example it comes from, with no Help Center article; the rest of the family sits on the Claude connectors hub. Anthropic reminds you on every sheet that it doesn't vouch for how the exposed tools behave, even when Anthropic is the publisher.
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