@cyanheads/stackexchange-mcp-server
Search Stack Exchange questions, fetch complete Q&A threads as clean markdown, browse tag FAQs, and look up user profiles via MCP. STDIO or Streamable HTTP.
5 Tools
Overview
Stack Exchange network access β Stack Overflow, Super User, Server Fault, Unix & Linux, and the wider network. Search questions, fetch complete Q&A threads as clean markdown, browse tag FAQs, and look up user profiles from any MCP client. Runs as a stdio process, a local Streamable HTTP server, or the public hosted endpoint above.
| Tool | Description |
|---|
stackexchange_search_questions | Search questions across a Stack Exchange site with full-text query, tag filters, score threshold, and sort order |
stackexchange_get_thread | Fetch a question and its answers as markdown, with a configurable answer limit and the accepted answer first |
stackexchange_get_tag_faq | Fetch the highest-voted answered questions for a tag β the canonical "best answers in X" list |
stackexchange_get_user | Fetch a user profile by ID: reputation, badge counts, top tags by answer score, and account metadata |
stackexchange_list_sites | Enumerate all Stack Exchange network sites and their api_site_parameter values |
Capability reference
- Full-text query with optional tag filters, minimum score threshold, and accepted-only filter; sort by relevance (default), votes, activity, or newest
- Up to 30 results per page (default 10);
page for more β each page costs one API quota unit, and paging past 25 requires STACKEXCHANGE_API_KEY
- Returns question ID, title, score, answer count, tags, and a ~300-character excerpt β IDs flow directly into
stackexchange_get_thread
- Quota remaining and max surfaced via enrichment on every response
- Accepts a numeric question ID or a full Stack Exchange question URL; fetches the question and a page of
maxAnswers answers (1β100, default 10), adding the accepted answer if it falls outside that page
- HTMLβmarkdown normalization built in β code blocks, links, lists, headers, and blockquotes all converted
- Optional
includeComments fetches up to 20 comments per post, newest first, using two extra API calls (one when there are no answers); commentsTruncated reports partial lists
- Attribution (author name, profile link, score) on every answer per CC BY-SA 4.0
- Quota remaining and max surfaced via enrichment;
truncated when more answers exist upstream than maxAnswers returned
- Highest-voted answered questions for a tag β maps to
/tags/{tag}/faq, the canonical "best answers in X" list
- Up to 30 results per page (default 10);
page for more β each page costs one API quota unit, and paging past 25 requires STACKEXCHANGE_API_KEY
- Returns a question list without bodies; pipe any
questionId into stackexchange_get_thread for full content
- Quota remaining and max surfaced via enrichment on every response
userId must be at most 2,147,483,647 (32-bit) β typically the authorUserId from stackexchange_get_thread output
- Fetches the profile and top tags in two upstream API calls
- Returns reputation, badge counts (gold/silver/bronze), location, website, answer/question counts, and up to 10 top tags by answer score (empty array for users with no answers)
- An unknown user ID returns a typed
user_not_found error β Stack Exchange answers HTTP 200 with empty results rather than 404
- Fetches every site in the Stack Exchange network, walking pages of 100 up to a 10-page cap; an enrichment notice flags a partial list if the network still has more
- Optional case-insensitive name filter matches against site name and
api_site_parameter, applied client-side after the fetch
- Returns the
api_site_parameter value (e.g. stackoverflow, superuser, serverfault) that every other tool's site parameter accepts
Features
Built on @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.
Stack Exchange-specific:
- HTMLβmarkdown conversion preserves code blocks, tables, links, images, and nested lists
- Shared upstream queue honors response backoff and HTTP 429 cooldowns; each operation has a 50-second budget covering queue time, backoff, requests, and retries
- Quota logging:
quota_remaining and quota_max surfaced via enrichment on every tool call
- Typed error contracts on every tool β
invalid_site, invalid_parameter, invalid_api_key, invalid_id_or_url, invalid_user_id, question_not_found, user_not_found, paging_depth_limit, quota_exceeded, and upstream_unavailable
- Optional
STACKEXCHANGE_API_KEY lifts the per-IP quota from ~300/day to ~10,000/day with no OAuth required
Agent-friendly output:
- Quota remaining on every response β agents can plan around rate limits without the server needing to fail
- The accepted answer appears first, followed by the remaining answers sorted by score
- Each answer includes attribution under CC BY-SA 4.0
- Typed
not_found errors for missing questions and users (SE returns HTTP 200 with empty items[] rather than 404)
Getting started
Public Hosted Instance
A public instance is available at https://stackexchange.caseyjhand.com/mcp β no installation required. Point any MCP client at it via Streamable HTTP:
{
"mcpServers": {
"stackexchange-mcp-server": {
"type": "streamable-http",
"url": "https://stackexchange.caseyjhand.com/mcp"
}
}
}
Self-Hosted / Local
Add the following to your MCP client configuration file.
{
"mcpServers": {
"stackexchange": {
"type": "stdio",
"command": "bunx",
"args": ["@cyanheads/stackexchange-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
Or with npx (no Bun required):
{
"mcpServers": {
"stackexchange": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@cyanheads/stackexchange-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
Or with Docker:
{
"mcpServers": {
"stackexchange": {
"type": "stdio",
"command": "docker",
"args": [
"run", "-i", "--rm",
"-e", "MCP_TRANSPORT_TYPE=stdio",
"ghcr.io/cyanheads/stackexchange-mcp-server:latest"
]
}
}
}
For Streamable HTTP, set the transport and start the server:
MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
Rate limits: The Stack Exchange API allows ~300 requests/day per IP without a key. Set STACKEXCHANGE_API_KEY in env to lift this to ~10,000/day. Register a key at stackapps.com/apps/oauth/register (the OAuth flow is only required for write access β a key alone is sufficient for read-only use).
Prerequisites
- Bun v1.4.0 or higher (or Node.js v24+)
- A
STACKEXCHANGE_API_KEY is optional but strongly recommended for any sustained use
Installation
- Clone the repository:
git clone https://github.com/cyanheads/stackexchange-mcp-server.git
- Navigate into the directory:
cd stackexchange-mcp-server
- Install dependencies:
- Configure environment:
Configuration
| Variable | Description | Default |
|---|
STACKEXCHANGE_API_KEY | Optional. Stack Exchange API key β lifts per-IP quota from ~300/day to ~10,000/day. | β |
MCP_TRANSPORT_TYPE | Transport: stdio or http. | stdio |
MCP_HTTP_PORT | Port for HTTP server. | 3010 |
MCP_HTTP_HOST | Host for HTTP server. | 127.0.0.1 |
MCP_SESSION_MODE | HTTP session mode: auto, stateful, or stateless. auto resolves to stateful. A meaningful env value overrides this server's stateless source default; blank or unsubstituted placeholders use the source default. | stateless |
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). | <project-root>/logs |
STORAGE_PROVIDER_TYPE | Storage backend. | in-memory |
OTEL_ENABLED | Enable OpenTelemetry instrumentation (spans, metrics, completion logs). | false |
See .env.example for the full list of optional overrides.
Running the server
Local development
-
Build and run:
bun run rebuild
bun run start:stdio
bun run start:http
-
Run checks and tests:
bun run devcheck
bun run test
bun run lint:mcp
Docker
docker build -t stackexchange-mcp-server .
docker run --rm -e STACKEXCHANGE_API_KEY=your-key -p 3010:3010 stackexchange-mcp-server
The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/stackexchange-mcp-server. OpenTelemetry peer dependencies are installed by default β build with --build-arg OTEL_ENABLED=false to omit them.
Project structure
| Path | Purpose |
|---|
src/index.ts | createApp() entry point β registers tools and inits services. |
src/config/ | Server-specific environment variable parsing with Zod (STACKEXCHANGE_API_KEY). |
src/mcp-server/tools/ | Tool definitions (*.tool.ts). |
src/services/stackexchange/ | Stack Exchange API v2.3 HTTP client, backoff tracking, quota logging, HTMLβmarkdown normalizer. |
tests/ | Vitest unit and integration tests. |
docs/ | Design document and directory tree. |
Development guide
See CLAUDE.md/AGENTS.md for development guidelines and architectural rules. The short version:
- Handlers throw, framework catches β no
try/catch in tool logic
- Use
ctx.log for request-scoped logging, ctx.state for tenant-scoped storage
- Register new tools via the barrel in
src/mcp-server/tools/definitions/index.ts
- Wrap external API calls: validate raw β normalize to domain type β return output schema; never fabricate missing fields
Contributing
Issues are welcome. Run checks and tests before submitting:
bun run devcheck
bun run test
License
Apache-2.0 β see LICENSE for details.