@cyanheads/gutenberg-mcp-server
Search, browse, and read 78,000+ public-domain books from Project Gutenberg with full plain-text retrieval and offset/limit chunking via MCP. STDIO or Streamable HTTP.
4 Tools
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[](https://www.npmjs.com/package/@cyanheads/mcp-ts-core)
**Public Hosted Server:** [https://gutenberg.caseyjhand.com/mcp](https://gutenberg.caseyjhand.com/mcp)
---
## Overview
Project Gutenberg's library of 78,000+ public-domain books. Search by title, author, topic, or language, fetch full book metadata, and read supported UTF-8 plain-text and HTML editions in manageable chunks.
### Tools
| Tool | Description |
|:-----|:------------|
| `gutenberg_search_books` | Search the catalog by title, author, topic, translator, language, or author lifespan, with pagination and popularity sorting |
| `gutenberg_get_book` | Fetch complete metadata for a book by ID — authors, translators, editors, full formats map, subjects, copyright status |
| `gutenberg_get_text` | Retrieve a book's plain-text content stripped of license boilerplate, with offset/limit chunking or a `find` jump to a passage |
| `gutenberg_browse_popular` | Browse the most-downloaded books, optionally filtered by language or topic |
The published [gutenberg-guide](./skills/gutenberg-guide/SKILL.md) skill covers deciding whether a book can be read, ruling out search blind spots before calling a book missing, finding openings and chapters past front matter, paging long texts, and ranking editions. Plugin installs include it; MCP clients can discover it through the Skills extension and its skill resource.
---
## Capability reference
### `gutenberg_search_books` tool
- Filters: `query` (title/author words), `topic`, `translator`, `languages` (catalog codes exactly as results report them, two or three letters: `en`, not `eng`), `author_year_start`/`author_year_end`, `ids`, `mime_type`, and `copyright` (`"true"`, `"false"`, `"null"`; false means public domain in the USA). Live fallback rejects queries over four words and the `translator` filter
- With both author-year bounds, one author must meet both. The live fallback checks the bounds separately and says so in a notice
- `sort` is `popular` (default) or `ascending`/`descending` by Gutenberg ID. Up to 32 books per page; use `totalCount` and `hasMore` to page
- Each result carries `is_readable` (eligible Text formats; mirror file availability is not guaranteed) and `has_plain_text`. The local mirror ignores case and accents in query, translator and topic matching; live matching is upstream-defined. Result rows omit translators; `gutenberg_get_book` reports them. Fails with `translator_requires_mirror`, `query_requires_mirror`, `page_out_of_range`, or `catalog_unavailable`
---
### `gutenberg_get_book` tool
- Returns the full `formats` map (MIME type → download URL) and authors, translators, and editors with birth/death years
- Also carries `is_readable`, `has_plain_text`, `summary`, `source_notes`, and `download_count` (downloads in the last 30 days, not lifetime)
- Fails with `not_found` or `catalog_unavailable`
---
### `gutenberg_get_text` tool
- Reads a book in `offset`/`limit` chunks (default `limit` 20,000, capped at 50,000), with the Gutenberg license header and footer stripped. `requestedLimit` and `appliedLimit` report both
- Prefers UTF-8 plain text and falls back to HTML converted to text; `sourceFormat` says which. Returns `totalChars`, `length`, `remainingChars`, `hasMore`, and `provenance` (ID, title, license URL). Use `length`, not `limit`, to compute the next `offset`
- `find` jumps to a passage instead of paging to it: the chunk starts at the first match at or after `offset`, and `match` reports its `offset`, `length`, and `laterMatches`. Matching ignores letter case and whitespace runs, and treats straight and curly quotes alike; accents and punctuation must match
- Converted HTML editions blank every line that holds no visible character and keep each table row on one line, with tab-separated cells
- Fails with `not_found`, `audio_book` (`media_type "Sound"`), `no_text_format`, `offset_out_of_range`, `passage_not_found`, `text_file_not_found`, `text_fetch_rejected`, `invalid_text_response`, `text_fetch_failed`, or `catalog_unavailable`
---
### `gutenberg_browse_popular` tool
- Returns up to 32 titles (`limit`, default 20), most downloaded in the last 30 days first. `requestedLimit` and `appliedLimit` report the cap
- Optional `languages`, `topic`, `mime_type`, and `copyright` filters work as in search. `totalInCatalog` gives the full count
- Output reports truncation and carries a `continuation` pointing at `gutenberg_search_books`. Empty results succeed with a notice; fails with `catalog_unavailable`
---
## Features
Built on [`@cyanheads/mcp-ts-core`](https://github.com/cyanheads/mcp-ts-core): stdio and Streamable HTTP transports, pluggable auth (`none` / `jwt` / `oauth`), swappable storage (`in-memory`, `filesystem`, `Supabase`, `Cloudflare KV/R2/D1`), structured logging with optional OpenTelemetry tracing.
Gutenberg-specific:
- Searches and lookups read a local SQLite+FTS5 catalog mirror, falling back to [Gutendex](https://gutendex.com/) when the mirror is cold or missing a record
- Full plain-text retrieval from a Project Gutenberg content mirror, with UTF-8/HTML fallback
- Book text is cached per tenant, so later chunk reads skip the fetch
- No API key required
Agent-friendly output:
- `is_readable` flags Text records with UTF-8 plain text, or HTML without audio formats; a missing mirror file still returns `text_file_not_found`
- `offset`, `length`, `totalChars`, `remainingChars`, and `hasMore` support reliable sequential reads
- `provenance` and `sourceFormat` on every text response cover attribution and fidelity
---
## Getting started
Connect to the hosted instance, no install:
```sh
claude mcp add --transport http gutenberg-mcp-server https://gutenberg.caseyjhand.com/mcp
```
Or run it locally:
```sh
claude mcp add gutenberg-mcp-server -- npx -y @cyanheads/gutenberg-mcp-server
```
For other clients, add this to the MCP config file:
```json
{
"mcpServers": {
"gutenberg-mcp-server": {
"command": "npx",
"args": ["-y", "@cyanheads/gutenberg-mcp-server"]
}
}
}
```
No API key required. For Docker or a source build, see [Running the server](#running-the-server).
---
## Configuration
| Variable | Description | Default |
|:---------|:------------|:--------|
| `GUTENDEX_BASE_URL` | Gutendex catalog API base URL. | `https://gutendex.com/books/` |
| `GUTENBERG_TEXT_BASE_URL` | Content mirror serving the `/cache/epub` file tree. | `https://gutenberg.pglaf.org` |
| `GUTENBERG_MIRROR_PATH` | SQLite catalog path; use a persistent volume in containers. | `./.mirror/gutenberg-catalog.sqlite` |
| `GUTENBERG_MIRROR_REFRESH_CRON` | Cron schedule for in-process catalog refresh. | Unset |
| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http`. | `stdio` |
| `MCP_SESSION_MODE` | HTTP session mode: `auto`, `stateful`, or `stateless`. Overrides the `stateless` posture the server declares in `createApp()`. | `stateless` |
| `MCP_HTTP_PORT` | Port for HTTP server. | `3010` |
| `MCP_AUTH_MODE` | Auth mode: `none`, `jwt`, or `oauth`. | `none` |
| `MCP_LOG_LEVEL` | Log level (RFC 5424). | `info` |
| `LOGS_DIR` | Directory for log files (Node.js only). | `/logs` |
| `STORAGE_PROVIDER_TYPE` | Storage backend. | `in-memory` |
| `OTEL_ENABLED` | Enable [OpenTelemetry instrumentation](https://github.com/cyanheads/mcp-ts-core/tree/main/docs/telemetry). | `false` |
Build the local catalog with `bun run mirror:init` and check it with `bun run mirror:verify`. The server never harvests on startup, and uses Gutendex until the first harvest completes. Keep the catalog up to date with `bun run mirror:refresh` on a host scheduler, or set `GUTENBERG_MIRROR_REFRESH_CRON`.
---
## Running the server
### Local development
Requires [Bun v1.4.0](https://bun.sh/) or higher (or Node.js v24+).
- **Clone and install:**
```sh
git clone https://github.com/cyanheads/gutenberg-mcp-server.git
cd gutenberg-mcp-server && bun install
cp .env.example .env # optional overrides
```
- **Build and run:**
```sh
# One-time build
bun run rebuild
# Run the built server
bun run start:stdio
# or
bun run start:http
```
- **Run checks and tests:**
```sh
bun run devcheck # Lint, format, typecheck, security
bun run test # Vitest test suite
bun run lint:mcp # Validate MCP definitions against spec
```
### Docker
```sh
docker run --rm -p 3010:3010 ghcr.io/cyanheads/gutenberg-mcp-server:latest
```
The image defaults to HTTP transport, stateless session mode, and logs to `/var/log/gutenberg-mcp-server`. To run it over stdio from an MCP client, use `"command": "docker"` with `"args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/gutenberg-mcp-server:latest"]`. To build locally, `docker build -t gutenberg-mcp-server .`; OpenTelemetry peer dependencies are installed by default — build with `--build-arg OTEL_ENABLED=false` to omit them.
---
## Project structure
| Directory | Purpose |
|:----------|:--------|
| `src/index.ts` | `createApp()` entry point — registers tools and inits services. |
| `src/config/server-config.ts` | Server-specific environment variable parsing (Gutendex and file-server URL overrides). |
| `src/mcp-server/tools/definitions/` | Tool definitions (`*.tool.ts`). |
| `src/services/gutendex/` | Gutendex catalog API client — search and book metadata. |
| `src/services/catalog-mirror/` | Local SQLite+FTS5 catalog mirror — RDF ingestion and read helpers. |
| `src/services/gutenberg-text/` | Full plain-text retrieval, boilerplate stripping, tenant-scoped caching, and chunking. |
| `skills/gutenberg-guide/` | Published agent skill for reading and discovery workflows, also served over MCP. |
| `tests/` | Unit and integration tests mirroring `src/`. |
---
## Development guide
See [`CLAUDE.md`](./CLAUDE.md) / [`AGENTS.md`](./AGENTS.md) for development guidelines and architectural rules. The short version:
- Handlers throw, framework catches — no `try/catch` in tool logic
- Use `ctx.log` for request-scoped logging, `ctx.state` for tenant-scoped storage
- Register new tools via the entry arrays in `src/index.ts`
- Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields
---
## Contributing
Issues are welcome. Run checks and tests before submitting:
```sh
bun run devcheck
bun run test
```
---
## Data attribution
Data from [Project Gutenberg](https://www.gutenberg.org/) is in the public domain. Catalog metadata sourced from [Gutendex](https://gutendex.com/) (MIT license).
---
## License
Apache-2.0 — see [LICENSE](LICENSE) for details.