@cyanheads/gutenberg-mcp-server
Search, browse, and read 75,000+ 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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**Public Hosted Server:** [https://gutenberg.caseyjhand.com/mcp](https://gutenberg.caseyjhand.com/mcp)
---
## Overview
Project Gutenberg's library of 78,000+ public-domain books, cataloged through the Gutendex API and served from a Gutenberg content mirror. Search by title, author, topic, or language, fetch full book metadata, and retrieve plain-text content in offset/limit chunks for long works from any MCP client. Runs as a stdio process, a local Streamable HTTP server, or the public hosted endpoint above.
### Tools
| Tool | Description |
|:-----|:------------|
| `gutenberg_search_books` | Search the catalog by title, author, topic, 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 |
| `gutenberg_browse_popular` | Browse the most-downloaded books, optionally filtered by language or topic |
---
## Capability reference
### `gutenberg_search_books` tool
- Free-text `query` matches titles and author names; `topic` matches subjects/bookshelves separately from `query`
- Filters: `languages` (ISO 639-1 codes), `author_year_start`/`author_year_end` lifespan range, `ids` for a batch lookup by known ID list
- `sort`: `popular` (default, by download count) or `ascending`/`descending` by Gutenberg ID
- Paginated — up to 32 books per page; `totalCount` and `hasMore` drive further pages
- Each result carries `has_plain_text` to pre-filter before calling `gutenberg_get_text`
- Typed failures: `no_results`, `page_out_of_range`, `catalog_unavailable`
---
### `gutenberg_get_book` tool
- Returns the full `formats` map (MIME type → download URL) — plain text, HTML, EPUB, cover image
- Authors, translators, and editors each carry birth/death years
- `has_plain_text` confirms a UTF-8 plain-text format exists; `media_type` distinguishes text books from audio (`"Sound"`)
- `summary` is the first entry of Gutendex's `summaries` array — both are `null`/empty when Gutendex has none
- Typed failures: `not_found`, `catalog_unavailable`
---
### `gutenberg_get_text` tool
- `offset`/`limit` chunking (limit 1–50,000, default 20,000) for works that routinely run 500KB–2MB
- Strips the standard Gutenberg license header and footer before chunking
- Prefers UTF-8 plain text; falls back to an HTML-to-text conversion (`sourceFormat` reports which)
- Response carries `totalChars`, `length`, `remainingChars`, `hasMore` — use `length`, not `limit`, to compute the next `offset`, since paragraph-boundary trimming can return slightly less than requested
- `provenance` carries the Gutenberg ID, title, and license URL for attribution
- Typed failures: `not_found`, `audio_book` (refuses `media_type "Sound"`), `no_text_format`, `offset_out_of_range`, `text_fetch_failed`, `catalog_unavailable`
---
### `gutenberg_browse_popular` tool
- Returns up to 32 titles (`limit`, default 20) ordered by download count, most popular first
- Optional `languages` and `topic` filters, applied together
- `totalInCatalog` gives full context (e.g. "top 20 of 60,000")
- Enrichment reports whether results were truncated and the download-count ceiling of the least-popular book shown, pointing to `gutenberg_search_books` to page through the rest
- Typed failures: `no_results`, `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:
- Catalog search and metadata via [Gutendex](https://gutendex.com/), an unofficial but stable JSON API over the Gutenberg dataset
- Single-book lookups (`gutenberg_get_book`, `gutenberg_get_text`) read from a local SQLite+FTS5 catalog mirror when it holds the record, falling back to the live Gutendex API otherwise
- Full plain-text retrieval from a Project Gutenberg content mirror that permits automated access, with transparent UTF-8/HTML fallback
- Tenant-scoped text caching — book text is fetched once per tenant and served from cache for subsequent chunk reads
- No API key required
Agent-friendly output:
- `has_plain_text` flag on every search/browse result lets agents pre-filter before attempting text retrieval
- Precise chunking contract on `gutenberg_get_text` — `offset`, `length`, `totalChars`, `remainingChars`, `hasMore` for reliable sequential reads
- `provenance` and discriminated `sourceFormat` fields on every text response, for attribution and fidelity awareness
- `gutenberg_browse_popular` enrichment reports truncation state and the download-count ceiling of omitted results
---
## Getting started
### Public Hosted Instance
A public instance is available at `https://gutenberg.caseyjhand.com/mcp` — no installation required. Point any MCP client at it via Streamable HTTP:
```json
{
"mcpServers": {
"gutenberg-mcp-server": {
"type": "streamable-http",
"url": "https://gutenberg.caseyjhand.com/mcp"
}
}
}
```
### Self-Hosted / Local
No API key required. Add the following to your MCP client configuration file:
```json
{
"mcpServers": {
"gutenberg-mcp-server": {
"type": "stdio",
"command": "bunx",
"args": ["@cyanheads/gutenberg-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with npx (no Bun required):
```json
{
"mcpServers": {
"gutenberg-mcp-server": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@cyanheads/gutenberg-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with Docker:
```json
{
"mcpServers": {
"gutenberg-mcp-server": {
"type": "stdio",
"command": "docker",
"args": [
"run", "-i", "--rm",
"-e", "MCP_TRANSPORT_TYPE=stdio",
"ghcr.io/cyanheads/gutenberg-mcp-server:latest"
]
}
}
}
```
For Streamable HTTP, set the transport and start the server:
```sh
MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp
```
### Prerequisites
- [Bun v1.3.0](https://bun.sh/) or higher (or Node.js v24+).
- No API key required — Project Gutenberg data is freely available.
### Installation
1. **Clone the repository:**
```sh
git clone https://github.com/cyanheads/gutenberg-mcp-server.git
```
2. **Navigate into the directory:**
```sh
cd gutenberg-mcp-server
```
3. **Install dependencies:**
```sh
bun install
```
4. **Configure environment:**
```sh
cp .env.example .env
# edit .env if you need to override any defaults
```
---
## Configuration
| Variable | Description | Default |
|:---------|:------------|:--------|
| `GUTENDEX_BASE_URL` | Base URL for the Gutendex catalog API. Override for self-hosted instances. | `https://gutendex.com/books/` |
| `GUTENBERG_TEXT_BASE_URL` | Base URL for a Project Gutenberg content mirror serving the `/cache/epub` file tree. Override to use a different mirror. | `https://gutenberg.pglaf.org` |
| `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` |
See [`.env.example`](./.env.example) for the full list of optional overrides.
---
## Running the server
### Local development
- **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 build -t gutenberg-mcp-server .
docker run --rm -p 3010:3010 gutenberg-mcp-server
```
The Dockerfile defaults to HTTP transport, stateless session mode, and logs to `/var/log/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. |
| `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.