@cyanheads/hn-mcp-server
Browse Hacker News feeds, threads, and user profiles with full-text search via MCP. STDIO or Streamable HTTP.
4 Tools
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**Public Hosted Server:** [https://hn.caseyjhand.com/mcp](https://hn.caseyjhand.com/mcp)
---
## Overview
Hacker News feeds, threads, and profiles. Browse ranked feeds, read full comment threads, look up users, and search stories, comments, polls, and jobs by keyword, author, date, or score.
### Tools
| Tool | Description |
|:---|:---|
| `hn_get_stories` | Fetch stories from an HN feed (top, new, best, ask, show, jobs), with title, URL, score, author, and comment count |
| `hn_get_thread` | Get an item and its comment tree as a threaded discussion, with depth and comment-count controls and a cursor to page through long threads |
| `hn_get_user` | Fetch a user profile with karma, about, and optionally a page of resolved submissions |
| `hn_search_content` | Search stories, comments, polls, and jobs via Algolia by keyword, by filters alone, or both — type, author, parent story, date range, and minimum points |
## Capability reference
### `hn_get_stories` tool
- Six feed types: `top`, `new`, `best`, `ask`, `show`, `jobs`; `count` (default 30) and `offset` for pagination. One call serves at most 100 stories; a `count` up to 1,000 is served at 100, with a `notice` naming the next `offset`
- Returns id, type, title, url, domain, score, author, timestamp, comment count, and body text — each field omitted (not null) when HN doesn't provide it
- Enrichment reports `total`, `offset`, and `hasMore`; while more stories remain, `truncated` is set and `notice` names the next `offset`, and a `notice` explains empty pages (empty feed, offset past end, or every item on the page deleted/flagged). The last page carries no truncation
- Items whose fetch failed after retries are listed in `failedIds` with a `notice` naming the retry; a page where every item failed returns the classified upstream error instead of an empty list
---
### `hn_get_thread` tool
- `itemId` plus `depth` (default 3; 0 returns the item with no comments) and `maxComments` (default 50) capping one response across all levels, alongside a fixed 64,000-byte text budget that cuts only between comments. One call resolves at most 10 levels and 200 comments; a `depth` up to 100 is served at 10 and a `maxComments` up to 1,000 at 200, with a `notice` naming the comment to pass as `itemId` or the `nextCursor` that reaches the rest
- Breadth-first traversal ranked like HN — top-ranked top-level comments resolve first, replies fill in only after the level above is exhausted
- Resumable: a response stopped by `maxComments`, the byte budget, or an upstream rate limit returns `nextCursor`; passing it back as `cursor` with the same `itemId` continues at the next unseen comment. The cursor carries the unvisited comments themselves, so re-ranked replies cannot shift it, and the server keeps no session state. A cursor the tool did not issue, an altered one, or one passed with a different `itemId` fails with `invalid_cursor`
- The root carries its relationships and state: `parent` and `storyId` (the story or poll the discussion belongs to) for a comment, `poll` for a poll option, `parts` and resolved `options` (text and votes, at every depth) for a poll, and `deleted`/`dead` markers. The `content[]` heading names the type — a title, `Comment by `, `Poll option by on poll ` — and marks a deleted or dead root
- Flat comment list carries `depth`/`parentId` for tree reconstruction, plus `childCount` and an `isOp` flag when the comment author submitted the thread's story — on a comment root, the story at `storyId`, never the comment's own author. Dead and deleted comments are left out, but their live replies are still returned at their true `depth`, with `parentId` naming the omitted comment
- `truncated` and `truncationReason` (`count`, `size`, `rate_limited`, or `depth` when replies lie below the depth limit) are set only while comments remain unread — never on a terminal page, including a thread that loads in full at exactly the cap. `notice` reports deleted/dead comments omitted during traversal and the next step: the cursor, or a larger `depth` or a comment id as `itemId`, naming by ID any omitted comment whose replies the depth limit cut
- Comments and poll options whose fetch failed after retries are listed in `failedIds`, and `notice` names them with the retry; failed comments ride in `nextCursor`, so paging on retries them rather than skipping them. The root item is still returned, and a failure is never passed off as a `maxComments`/`depth` limit
---
### `hn_get_user` tool
- `username` is case-sensitive and trimmed; `includeSubmissions` (default false) resolves recent submissions, with `submissionCount` (default 10) and `submissionOffset` paging through a long history. One call resolves at most 50 submissions; a `submissionCount` up to 1,000 is served at 50, with a `notice` naming the next `submissionOffset`
- Profile includes karma, creation date, and about text (HTML stripped); submissions filter out dead/deleted items
- A comment submission carries its `parent` and a poll-option submission its `poll`, so either links back to what it answered
- Enrichment echoes `submissionOffset` and the offset to send next, or a notice when the requested offset is past the end of the history
- Submissions whose fetch failed after retries are listed in `failedIds` with a `notice` naming the retry; a window where every submission failed returns the classified upstream error
---
### `hn_search_content` tool
- Free-text `query` plus `tags` (`story`/`comment`/`poll`/`job`/`ask_hn`/`show_hn`/`front_page`), `author` (the exact, case-sensitive username), `storyId`, `dateRange`, and `minPoints` filters; `sort` by relevance or date; `count` (default 30) and `page` for pagination. One call serves at most 50 hits; a `count` up to 1,000 is served as the page of 50 starting at the requested page's first hit, with a `notice` naming the `count: 50` page to pass next; a non-zero `page` whose first hit begins no page of 50 fails with `count_page_unaligned`, naming a `count` and `page` that start there and, when that count is under 25, the page of 50 that holds that hit
- `tags: "front_page"` is the front page right now (about 30 stories), never past front pages; for an earlier window, use `tags: "story"` with `dateRange` and `minPoints`
- `query` is optional when a filter is set — list Ask HN, Show HN, polls, or jobs on their own, or pass a story's `storyId` with `tags: "comment"` to search within one thread. No query and no filter fails with `missing_query_or_filter`
- To check whether a page was discussed, pass its URL alone as `query`: the leading `http://`, `https://`, or `www.` is dropped before searching, so submissions under either scheme, with or without `www.`, all match. The output `query` and the notice show what was searched
- `dateRange` bounds take ISO 8601 (`YYYY`, `YYYY-MM`, `YYYY-MM-DD`, or a date-time with optional offset), read as UTC and both exclusive; an empty or out-of-order range fails with `invalid_date_range`
- `minPoints` applies to stories and polls — comments and jobs carry no points, so pairing it with `tags: "comment"` or `"job"` fails with `min_points_unscored_type`
- `view: "compact"` drops the two body-text fields (`text`, `highlights.text`), which otherwise repeat a long comment twice per hit — pass a hit id to `hn_get_thread` to read the body
- Each hit carries its `type` (`story`, `comment`, `poll`, `pollopt`, `job`) when Algolia records one. Untagged searches also return poll options, which carry only an id, author, vote count, and date — `hn_get_thread` reads an option's text and poll. A poll hit has no `storyId`; its own `id` is the discussion root
- Job descriptions come back as `text`, though keywords don't search them
- Highlight metadata (`highlights.title`, `highlights.text`, `matchedWords`) shows which terms matched and where
- Enrichment echoes the applied `criteria` — each filter set (`author` trimmed, `dateRange` as the exclusive UTC bounds applied, to the second), plus `sort`, `count`, and `view` with defaults filled — so a saved result says what it answers
- Enrichment reports `totalHits`, `page`, and the actual reachable `totalPages` — not derived from `totalHits`, since broad queries report far more hits than Algolia will serve. `totalHitsExact: false` marks `totalHits` as an estimate, and `reachableHits: 1000` marks a search that matches more than Algolia's 1,000-hit ceiling; the last page of such a search gets a notice naming the ceiling and narrower `dateRange` windows to reach the rest. While more pages remain, `truncated` is set and `notice` names the next `page`; a page past the end gets a notice naming the last valid page (or `page: 0` past the ceiling)
## 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.
HN-specific:
- Two upstream APIs: HN's Firebase API for feeds, items, and users; Algolia's HN Search API for full-text search
- Concurrent batch fetching with configurable parallelism for item resolution (`HN_CONCURRENCY_LIMIT`)
- HTML bodies stripped to plain text — entities decoded once, code blocks kept verbatim, each link rendered once as its full URL — while titles, which are not HTML though some carry entities, are entity-decoded and never tag-stripped
- Server-level `instructions` forwarded to LLM clients on `initialize` — item types, ID reuse across tools, case-sensitive usernames, field sparsity
- No API keys required — both upstream APIs are public
Agent-friendly output:
- Graceful partial failure — an item whose fetch fails after retries is reported by ID in `failedIds`, apart from deleted, dead, or nonexistent items, rather than silently shrinking the result; `hn_get_thread` also counts the deleted and dead comments it drops, and a rate-limited item stops the batch instead of sending every remaining item through its own retry ladder
- Discriminated output contracts — typed error reasons (`item_not_found`, `upstream_rate_limited`, `upstream_html`, …) with per-reason recovery text (a rate limit passes on the upstream's `Retry-After` as `retryAfter`), and a `depth`/`parentId` pair on every comment so callers reconstruct the tree without guessing nesting
- Pagination provenance — every paged listing echoes the offset it used (`offset`, `submissionOffset`, `page`) plus the exact next-offset value in `notice`, `hn_search_content` also echoes the `criteria` it searched with, and `hn_get_thread` returns a self-contained `nextCursor`, so an agent can resume without recomputing state
- Response shaping — HTML stripping, URL normalization, and domain extraction remove upstream markup noise; `hn_search_content`'s `view: "compact"` drops the two body-text fields that otherwise duplicate a hit's full text
- Fenced upstream text — in `content[]`, every line of a body is block-quoted and titles are escaped only where they could break the surrounding Markdown, so a comment cannot pass for a server-authored line
## Getting started
### Public Hosted Instance
A public instance is available at `https://hn.caseyjhand.com/mcp` — no installation required. Point any MCP client at it via Streamable HTTP:
```json
{
"mcpServers": {
"hn-mcp-server": {
"type": "streamable-http",
"url": "https://hn.caseyjhand.com/mcp"
}
}
}
```
### Self-Hosted / Local
Add to your MCP client configuration file:
```json
{
"mcpServers": {
"hn-mcp-server": {
"type": "stdio",
"command": "bunx",
"args": ["@cyanheads/hn-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with npx (no Bun required):
```json
{
"mcpServers": {
"hn-mcp-server": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@cyanheads/hn-mcp-server"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with Docker:
```json
{
"mcpServers": {
"hn-mcp-server": {
"type": "stdio",
"command": "docker",
"args": [
"run", "-i", "--rm",
"-e", "MCP_TRANSPORT_TYPE=stdio",
"ghcr.io/cyanheads/hn-mcp-server:latest"
]
}
}
}
```
### Prerequisites
- [Bun v1.4.0](https://bun.sh/) or higher (or Node.js >= 24)
### Installation
```sh
git clone https://github.com/cyanheads/hn-mcp-server.git
cd hn-mcp-server
bun install
```
## Configuration
All configuration is via environment variables. No API keys required — HN APIs are public.
| Variable | Description | Default |
|:---------|:------------|:--------|
| `HN_CONCURRENCY_LIMIT` | Max concurrent HTTP requests for batch item fetches (integer, 1–50). | `10` |
| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http`. | `stdio` |
| `MCP_HTTP_PORT` | HTTP server port. | `3010` |
| `MCP_HTTP_HOST` | HTTP server host. | `127.0.0.1` |
| `MCP_SESSION_MODE` | HTTP session handling: `stateful`, `stateless`, or `auto` (resolves to `stateful`). The server declares `stateless` in source, and the published Docker image and `.env.example` set it too; a meaningful env value still overrides. | `stateless` |
| `MCP_LOG_LEVEL` | Log level: `debug`, `info`, `notice`, `warning`, `error`. | `info` |
| `LOGS_DIR` | Directory for log files (Node.js only). | `/logs` |
See [`.env.example`](./.env.example) for the full list of optional overrides.
## Running the server
### Local development
- **Dev mode (auto-reload):**
```sh
MCP_TRANSPORT_TYPE=stdio bun --watch src/index.ts # stdio
MCP_TRANSPORT_TYPE=http bun --watch src/index.ts # HTTP
```
- **Build and run:**
```sh
bun run rebuild
bun run start:stdio # or start:http
```
- **Run checks and tests:**
```sh
bun run devcheck # Lint, format, typecheck, security
bun run test # Vitest test suite
```
### Docker
```sh
docker build -t hn-mcp-server .
docker run --rm -p 3010:3010 hn-mcp-server
```
The Dockerfile defaults to HTTP transport, stateless session mode, and logs to `/var/log/hn-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 the HN service. |
| `src/config/` | Server-specific environment variable parsing and validation with Zod. |
| `src/mcp-server/tools/definitions/` | Tool definitions (`*.tool.ts`). |
| `src/services/hn/` | HN Firebase + Algolia API client and domain types. |
| `tests/` | Unit and integration tests mirroring `src/`. |
## Development guide
See [`CLAUDE.md`](./CLAUDE.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
- All tools are read-only — no auth scopes required
- Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields
## Contributing
Issues are welcome. Run checks before submitting:
```sh
bun run devcheck
bun run test
```
## License
Apache-2.0 — see [LICENSE](LICENSE) for details.