# calibre-mcp MCP Server

Calibre ebook library server: search, read content, curate metadata, semantic search, gated writes.

**Publisher claimed.** No tool list reported, and Pod has not connected to this server.

## Status

Pod has not dialled calibre-mcp yet, so everything on this page is what its publisher reported rather than what we observed. Registries describe servers; they do not connect to them. Until a check runs, treat the tool list below as a claim.

## Connect

Published as `calibre-mcp` on npm. Runs locally.

## Known issues

**87 problems reported by people outside the maintainer team.** Issues filed by the project's own owners, members and collaborators are excluded — those are release checklists and internal refactors, not things that will go wrong for you. Showing 12.

### Most discussed

### Probe: ImageContent rendering + payload caps in Claude Desktop

## Question
HITL probe on Artem's Desktop via a dev .mcpb (mcpb-dev skill): do figure ImageContent blocks render in chat? Does the model demonstrably SEE them (ask it to describe a diagram)? Where does Desktop actually choke on payload size (validate the ~2 MB cap; find the real ceiling)? Does detail:high visibly improve label readability on a dense diagram? Record facts like spike #21 did. Done = verdict comment + any cap adjustments filed against the tool.

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/80) · 2026-07-22 · closed · 7 comments

### feat: figures widget — fetch mirror per approved mockup

## Question

Implement the widget: new `src/ui/figures-html.ts` built from the frozen **v2** mockup (`docs/dev/design/figures-widget-v2.html` — reading pane + margin rail, #114; the v1 contact sheet in #110 is superseded), registered as a `ui://` app resource and attached to `calibre_get_figures` via `_meta.ui.resourceUri`.

**Wire the MCP plumbing into the v2 mockup, don't redesign it.** The mockup leaves four seams (`figures-widget-v2.html:191`): `window.FIG.render(payload)`, `onToggleZoom(idx

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/112) · 2026-07-27 · closed · 4 comments

### get_content and content-layer tools fail after client restart while ping succeeds; missing @huggingface/transformers breaks more than semantic search

## Summary
After a Claude Desktop restart, content-related tools consistently fail with a generic tool execution error, while calibre_ping succeeds. Metadata and content tools (calibre_get_content, calibre_search mode=fts, calibre_get_book) all return errors on every call.

## Environment
- Client: Claude Desktop (macOS)
- Library: Programming_Books (~800 books), Calibre GUI + Content Server running on :8080
- Book used for repro: id 164, PDF (Software Architecture Metrics, OReilly)

## Repro / 

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/73) · 2026-07-21 · closed · 3 comments

### Search-inside buttons vanish after a successful click — ui/message success misread as failure

## What happened

In Claude Desktop (v0.6.0), clicking **Search inside** on the cover board sends the message to chat correctly (the assistant starts searching inside the book) — but afterwards the Search-inside affordance disappears from **every** card in the widget, in both the shelf and coverflow variants. Re-entering the chat restores them.

## What I expected

A successful click leaves the buttons in place. The message-backed buttons should only hide when the host genuinely can't deliver ch

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/72) · 2026-07-21 · closed · 3 comments

### Clicked Read button disappears from the book card after use (Claude Desktop)

## What happened

In Claude Desktop (v0.6.0 bundle), clicking a per-format **Read** button (e.g. Read PDF) on the book card opens Desktop's open-link confirmation dialog — and the clicked button disappears from the card. It happens regardless of whether the dialog is approved (book opens in the browser) or dismissed. Only the clicked button vanishes; the other format's Read/⬇ pair and the rest of the card stay. Leaving and re-entering the chat restores the button.

## What I expected

The button

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/69) · 2026-07-21 · closed · 3 comments

### Most recent

### Expose index generation (INDEX_VERSION) as citation provenance in semantic-search results + calibre_ping

### Problem

`calibre_semantic_search` returns locations (`bookId`, `format`, `charStart`/`charEnd`, and
`page` for figure hits) that are only meaningful **relative to the extraction + chunker
generation that produced the index**. That generation is tracked internally as
`INDEX_VERSION` (`src/semantic/model.ts:147`) and written into the index `meta` table
alongside `model_id`/`dim` (`src/semantic/store.ts:808`), but it is not exposed anywhere a
client can read:

- not in `calibre_semantic_search

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/136) · 2026-08-27 · open · 0 comments

### feat(structure): EPUB TOC (nav.xhtml/NCX) as a chapter-map source — needs spine-aware extraction

## Problem

An EPUB carries the best chapter structure of any format we handle — an explicit, authored
`nav.xhtml` (EPUB 3) or NCX (EPUB 2) table of contents, with real titles pointing at real
spine documents. We use **none of it**. Chapter detection
(`src/domain/structure/chapters.ts`) runs the same text heuristics over an EPUB as over a
scanned PDF, so a book whose TOC says "The Carpet-Bag" only gets a chapter span if that
string happens to look like a heading in the converted plain text.

## 

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/135) · 2026-08-21 · open · 0 comments

### feat(structure): use the PDF outline (bookmarks) as a chapter-map source

## Problem

Chapter detection (`src/domain/structure/chapters.ts`) is **purely text-based**: explicit
headings (`Chapter 5` / `Kapitel 5` / `Глава 5` / `第5章`), Roman numerals, or Markdown
`#`/`##`. A PDF that carries a perfectly good publisher outline (bookmarks) but never
writes the word "Chapter" in its body text comes back `detector: "none"` — no chapter map
for `calibre_get_content` mode=structure, no chapter walk for `calibre-distill`, and search
hits labelled by raw offset instead of a cha

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/134) · 2026-08-21 · open · 0 comments

### feat(extract): support ODT books (ebook-convert already handles them)

`FORMAT_PREFERENCE` in `src/calibre/extract.ts` currently ends at
`… docx, htmlz, fb2, rtf` — **`odt` is missing**, so a book whose only format is ODT is
reported as *"no extractable text format"* by `calibre_get_content`, `calibre_build_index`
and ISBN scanning, exactly like the `md` gap fixed in #131 / v0.7.4.

ODT is a first-class **input** format for Calibre's `ebook-convert` (the same backend that
already handles EPUB/MD/DOCX here), so this should be a one-line addition plus a test —
no new

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/132) · 2026-08-21 · open · 0 comments

### ui: clicking a cover on the cover board does nothing visible in Claude Desktop (widget-initiated tools/call result never reaches the chat)

## Symptom (Claude Desktop, live, 2026-08-18)

On the cover board (both shelf and coverflow), clicking a cover — the centered one in coverflow — shows the "Opening…" overlay for ~1.4 s and then **nothing happens**. No book card appears in the chat.

Reproduced while recording the new demo GIF: `which of my books explain consumer-group rebalancing?` → coverflow → click centered cover → nothing.

## Cause

`src/ui/board-html.ts` `onCardClick(bookId)` does a **widget-initiated** `tools/call calibre

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/130) · 2026-08-18 · closed · 1 comment

### Task: seed initial bundles + exclusion markers for Artem's library (curation session)

## Question

Run the first curation session over the real library (791 books): decide and create the initial topic bundles (e.g. rust, databases, architecture, ai/llm — drive from `calibre_list_categories` tag counts and `calibre_quality_report`) and the first `-` exclusion markers (noise/outdated books). HITL: bundle boundaries and what counts as noise are Artem's calls; the agent proposes from tag statistics, Artem confirms, `calibre_manage_bundles` writes. Done = a confirmed starter set live 

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/126) · 2026-08-03 · open · 0 comments

### Release: v2-based calibre-mcp ships + Desktop verification on the released bundle

## Question

Ship it and prove it live.

Cut the release via the `release` agent (version shape decided at this point, per the map's *Not yet specified*): version bump across all spots including `manifest.json` and `.claude-plugin/plugin.json`, CHANGELOG entry, tag, CI publish; then verify **npm + `.mcpb` + MCP Registry `isLatest`**.

Then verify live in **Claude Desktop on the released bundle**, not a dev one:

- server connects and all 18 tools are listed;
- a read round-trips (`calibre_search

[Read the thread](https://github.com/caelum29/calibre-mcp/issues/125) · 2026-07-28 · open · 0 comments

[See all 24 reports Pod holds for calibre-mcp](/mcp/calibre-mcp/issues) — of 87 qualified upstream.

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