Add pdf-viewer plugin with local MCP server by bryan-anthropic · Pull Request #72 · anthropics/knowledge-work-plugins

bryan-anthropic · 2026-02-23T16:26:34Z

Summary

Adds a pdf-viewer plugin that uses a local stdio MCP server (@modelcontextprotocol/server-pdf) instead of a remote HTTP connector
First plugin in this repo to use the local server pattern — all existing plugins use type: "http" remote connectors
Exposes the server's interact tool: 10 annotation types, form filling, visual signatures, stamps, page extraction
Registers the plugin in marketplace.json

What's in the plugin

File	Purpose
`.mcp.json`	Local MCP server via `npx -y @modelcontextprotocol/server-pdf --stdio`
`commands/open.md`	`/pdf-viewer:open` — open a PDF in the interactive viewer
`commands/annotate.md`	`/pdf-viewer:annotate` — propose markup, review together, iterate
`commands/fill-form.md`	`/pdf-viewer:fill-form` — fill form fields with live visual feedback
`commands/sign.md`	`/pdf-viewer:sign` — place signature/initials images
`skills/view-pdf/SKILL.md`	Unified skill: viewing, annotation, forms, signing workflows
`CONNECTORS.md`	Documents the local server setup

Positioning

The viewer's value is interactivity with the user — showing the document, collaborating on markup, live form feedback. The SKILL.md explicitly steers Claude toward native Read for pure summarization/extraction and toward the viewer for annotate/fill/sign/stamp workflows.

`.mcp.json` (the key difference)

{
  "mcpServers": {
    "pdf": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-pdf", "--stdio"]
    }
  }
}

Instead of "type": "http" + "url", this uses "command" + "args" to start a local process. Unpinned version pulls latest (currently 1.3.1, which includes the interact tool from ext-apps#506).

Test results

Tested end-to-end via claude --plugin-dir pdf-viewer/:

Component	Status
Plugin validation (`claude plugin validate`)	PASS
MCP server connection (local stdio)	PASS
`list_pdfs`, `display_pdf`, `interact` tools	PASS — all 7 tools registered
Commands registration	PASS (`/pdf-viewer:{open,annotate,fill-form,sign}`)
Skill registration	PASS (`pdf-viewer:view-pdf`)

Tool namespacing: mcp__plugin_pdf-viewer_pdf__<tool_name>

Open question: Cowork VM support

This works in Claude Code (desktop CLI). Unknown whether Cowork VMs support local stdio servers — all existing plugins use remote connectors, which may be a Cowork constraint or simply the pattern that's been used so far.

Test plan

Install: claude --plugin-dir pdf-viewer/
Verify MCP server connects and interact tool appears
/pdf-viewer:open with an arXiv URL
/pdf-viewer:annotate — verify propose→review loop works
/pdf-viewer:fill-form on a PDF with form fields
/pdf-viewer:sign with a signature image

First knowledge-work plugin to use a local stdio MCP server instead of a remote HTTP connector. The pdf-server runs locally via npx and provides interactive PDF viewing for academic papers and local files. Tested end-to-end in Claude Code: plugin validation, MCP server connection, tool availability (list_pdfs, display_pdf), and command/skill registration all confirmed working. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

The underlying @modelcontextprotocol/server-pdf gained an `interact` tool with 10 annotation types (highlight, underline, strikethrough, note, rectangle, circle, line, freetext, stamp, image), form filling, auto-highlight-text, page extraction, and annotated-PDF download. This reshapes the plugin around interactive workflows: - Rename plugin: pdf-research → pdf - Rename skill: pdf-reading → pdf (unified, covers all capabilities) - Commands: drop /summarize, rename /read → /open, add /annotate, /fill-form, /sign - SKILL.md: document interact tool, all annotation types, coordinate system, interactive workflows (AI-driven annotate, form filling, visual signing) - Positioning: explicitly steer AWAY from viewer for pure ingestion (use native Read instead) — the viewer's value is user interactivity - /sign disclaimer: visual signature image, not certified digital sig Out of scope (documented): summarization, cert signing, PDF generation.

Accuracy: - list_pdfs: 'remote origins' → 'local directories' (server has no remote allowlist, any HTTPS works) - get_screenshot: 'PNG' → 'image' (server returns JPEG) - Supported sources: clarify only arXiv auto-converts /abs/→PDF; others need direct PDF URLs Conventions (matching legal/, productivity/ patterns): - Add argument-hint frontmatter to all 4 commands - Add CONNECTORS.md callout to all commands Positioning — form filling: - Emphasize this is VISUAL form filling (vs programmatic tools) - Document the unnamed-field workflow: screenshot → match bounding boxes to visual labels → fill by name. Many real PDFs have fields named 'Text1', 'Field_7' with labels only on the rendered page. - User gets live feedback and can edit directly in viewer

Plugin name: pdf → pdf-viewer - 'Viewer' makes the interactive/visual modality self-evident - Naturally explains why NOT to use for summarization - Matches enterprise-search precedent (capability-named, not job-function) Skill name: pdf → view-pdf - Verb-noun matches repo convention (review-contract, triage-nda) Trigger description (SKILL.md frontmatter): - Hybrid style: situation framing + verb list for keyword matching - Includes 'open, show, view' so bare 'open this PDF' triggers the skill — SKILL body then disambiguates viewer vs Read - Keeps 'Not for summarization (use Read)' guard Marketplace/plugin.json description: - Marketing-oriented (benefits-first) to match other plugins' style - 'View, annotate, sign... Mark up contracts, fill forms with visual feedback, stamp approvals, place signatures — download annotated copy' Updated all /pdf:* cross-references → /pdf-viewer:*

…owledge-work-plugins This directory duplicated the Claude Code plugin that's being added to the knowledge-work plugin marketplace (anthropics/knowledge-work-plugins#72). Keeping a copy here meant two sources of truth drifting apart — this one is already stale vs. the server's interact/annotation capabilities from #506. The MCPB packaging (manifest.json) remains — that's the distributable server artifact. The Claude Code plugin wrapper belongs in the plugin marketplace repo where it can be versioned and discovered alongside other plugins. Note: committed with --no-verify because the pre-commit hook's 'xargs git add $STAGED' step fails on deletion-only commits (the paths no longer exist). Hook fix tracked separately.

…owledge-work-plugins (#565) This directory duplicated the Claude Code plugin that's being added to the knowledge-work plugin marketplace (anthropics/knowledge-work-plugins#72). Keeping a copy here meant two sources of truth drifting apart — this one is already stale vs. the server's interact/annotation capabilities from #506. The MCPB packaging (manifest.json) remains — that's the distributable server artifact. The Claude Code plugin wrapper belongs in the plugin marketplace repo where it can be versioned and discovered alongside other plugins. Note: committed with --no-verify because the pre-commit hook's 'xargs git add $STAGED' step fails on deletion-only commits (the paths no longer exist). Hook fix tracked separately.

Without -y, npx prompts 'Ok to proceed? (y)' on first install of a package, which hangs the stdio MCP connection (no TTY to answer). Keeping version unpinned (auto-latest) — currently pulls 1.3.1 which has the interact/annotation capabilities. Tested end-to-end via 'claude --plugin-dir pdf-viewer/'.

Rescope pdf-research → pdf-viewer: expose annotation, form-filling, signing

Upstream added 28 plugins since February (partners, URL-source). Keep all upstream entries, append pdf-viewer. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ochafik

Thanks @bryan-anthropic !

bryan-anthropic and others added 4 commits February 23, 2026 10:25

ochafik mentioned this pull request Mar 24, 2026

Remove examples/pdf-server/plugin/ — canonical copy is upcoming in knowledge-work-plugins modelcontextprotocol/ext-apps#565

Merged

ochafik mentioned this pull request Mar 25, 2026

Rescope pdf-research → pdf-viewer: expose annotation, form-filling, signing bryan-anthropic/knowledge-work-plugins#1

Merged

ochafik and others added 3 commits March 25, 2026 17:17

Rescope pdf-research → pdf-viewer: annotation, form-fill, sign commands

f0c53a1

Rescope pdf-research → pdf-viewer: expose annotation, form-filling, signing

Merge upstream main: resolve marketplace.json conflict

fc8d9b2

Upstream added 28 plugins since February (partners, URL-source). Keep all upstream entries, append pdf-viewer. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ochafik changed the title ~~Add pdf-research plugin with local MCP server~~ Add pdf-viewer plugin with local MCP server Mar 27, 2026

ochafik approved these changes Mar 27, 2026

View reviewed changes

ochafik merged commit f55b539 into anthropics:main Mar 28, 2026

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Add pdf-viewer plugin with local MCP server#72

Add pdf-viewer plugin with local MCP server#72
ochafik merged 7 commits intoanthropics:mainfrom
bryan-anthropic:add-pdf-research-plugin

bryan-anthropic commented Feb 23, 2026 •

edited by ochafik

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bryan-anthropic commented Feb 23, 2026 • edited by ochafik Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

What's in the plugin

Positioning

.mcp.json (the key difference)

Test results

Open question: Cowork VM support

Test plan

Related

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bryan-anthropic commented Feb 23, 2026 •

edited by ochafik

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`.mcp.json` (the key difference)