Open Archives

Open Archives MCP Server

Production-grade hybrid MCP + HTTP + SSE server generated from the Open Archives OpenAPI specification. Covers genealogical records (births, deaths, marriages, censuses), archive statistics, historical weather, and full-text page transcriptions of historical documents.

OpenAPI source used to generate tools:

../api/openapi.yaml   (local)https://api.openarchieven.nl/openapi.yaml   (remote)

Overview

A schema-aware server that automatically converts the OpenAPI specification into callable tools and exposes them through multiple transports:

• MCP Remote (JSON-RPC over StreamableHTTP)
• HTTP JSON API
• SSE streaming with auto-pagination
• Chunked HTTP streaming with auto-pagination
• Redis caching (optional)
• Health checks

Video (Dutch): Help AI met jouw erfgoedservices (via MCP)

Use with Claude

Add as a custom connector

A hosted endpoint is available — no installation required.

In claude.ai or Claude Desktop:

1. Open Settings → Connectors.
2. Click Add custom connector.
3. Enter the URL: https://mcp.openarchieven.nl/
4. Save and approve when prompted.

No authentication is required — Open Archives is a public dataset.

Example queries

Once the connector is added you can ask Claude, for example:

• "Who are the ancestors of Johannes Gregorius Marinus Coret? Give me an overview, including source citations in markdown format with the links to the original archives if possible, otherwise provide the Open Archieven links and provide a tree in SVG."
• "Did Johannes Coret and Antonia Uphus have descendants? Give me an overview, including source citations in markdown format with the links to the original archives if possible, otherwise provide the Open Archieven links, include thumbnails from scans from archival sources if available and provide a tree in SVG."
• "Provide me with a list of sourcetypes per archive(name) where I can find information about the Coret family. Show the result in a markdown document including links to the search pages on Open Archieven. Instead of the archive code use the ISIL if available."
• "What was the weather in Amsterdam on 1953-02-01?"
• "What does the 1850 census say about Utrecht?"

Claude will call the matching tool (search_records, show_record, get_marriages, get_historical_weather, get_census_data, …) and return links to the corresponding record pages on https://www.openarchieven.nl.

Self-hosted

The server speaks MCP over Streamable HTTP; there is no stdio distribution. To run your own instance:

git clone https://github.com/coret/openarchieven-mcp-server.gitcd openarchieven-mcp-servernpm installnpm run generate      # builds generated/tools.json from openapi.yamlnpm run build:viewer  # builds dist/viewer.html (the MCP App)npm start             # listens on http://localhost:3001/

Point your MCP client at http://localhost:3001/ (or your own public URL) the same way as the hosted endpoint above.

Core Features

OpenAPI Auto-Generation

Every API operation becomes a tool automatically via generate.ts.

All 21 operations:

Note: The callback (JSONP) parameter present in the upstream API is excluded from all tools — it is irrelevant in an MCP/JSON-RPC context.

Interactive Transcription Viewer (MCP App)

Beyond the 21 auto-generated tools, the server registers one hand-written tool — view_transcription — that opens transcribed pages in an interactive IIIF deep-zoom viewer (OpenSeadragon) with the transcription text alongside, using the MCP Apps extension (io.modelcontextprotocol/ui).

• Apps-capable hosts (Claude web/desktop, paid custom connectors) render the viewer (ui://openarchieven/viewer.html) in a sandboxed iframe that loads images directly from the transcription image hosts (CSP-allowlisted as *.transkribus.eu, *.archief.nl, *.archieven.nl, *.memorix.nl). Transkribus and the archief.nl iipsrv server provide true IIIF deep zoom; the preserve*.archieven.nl thumbnail hosts render as flat images.
• Plain hosts receive a graceful fallback: a text summary with the IIIF/source URLs plus a few inline preview images.

The viewer is a single self-contained dist/viewer.html, bundled at build time with npm run build:viewer (vite + vite-plugin-singlefile); it is not listed by the REST GET /tools endpoint, only via MCP tools/list.

Schema-Perfect Validation

Uses actual OpenAPI parameter schemas. Validates:

• required parameters
• integer fields
• number fields
• enum values
• minimum / maximum constraints

Multiple Interfaces

MCP Remote (StreamableHTTP)

POST /       ← canonical public endpoint (mcp.openarchieven.nl)POST /mcp    ← local / legacy alias

Stateless JSON-RPC transport — a new MCP server instance is created per request.

Origin validation: Browser requests must come from claude.ai, claude.com, or any domain listed in ALLOWED_ORIGINS. Requests with no Origin header (native MCP clients, curl, server-to-server) are accepted. Unknown origins receive HTTP 403.

HTTP JSON

GET  /toolsPOST /tools/:name

SSE Streaming (auto-paginating)

GET /events/:name

Chunked HTTP Streaming (auto-paginating)

POST /stream/:name

Discovery Metadata (/.well-known)

Static, hand-editable JSON files served verbatim from well-known/:

GET /.well-known/mcp/server-card.json   ← SEP-1649 MCP Server CardGET /.well-known/mcp.json               ← alias of the server cardGET /.well-known/agent-card.json        ← A2A v0.3 Agent CardGET /.well-known/agent.json             ← alias of the agent card

Edit well-known/mcp-server-card.json and well-known/agent-card.json directly — no restart required (files are read on each request). Responses are sent with Content-Type: application/json; charset=utf-8 and Cache-Control: public, max-age=3600.

Pagination

Streaming endpoints (/events/:name, /stream/:name) automatically paginate through results for endpoints that support a start offset:

• Increments start by number_show per page
• Stops when results are exhausted or after 20 pages (safety cap)
• SSE sends a : heartbeat comment every 10 seconds to keep connections alive

Redis Cache

Optional Redis support.

If Redis is running, upstream responses are cached with a per-tool TTL tuned to the data's volatility:

CACHE_TTL (default 3600) is the fallback for any tool not in the map above.

If Redis is unavailable:

• server still runs normally (degraded mode)

Rate Limiting

The upstream API enforces 4 requests per second per IP. The server queues all upstream calls through a token-bucket rate limiter (configurable via RATE_LIMIT_RPS).

Health Checks

GET /health

Project Files

generate.tsserver.tstsconfig.jsonpackage.json.env.examplegenerated/  tools.json  spec.json

Requirements

• Node.js 18+
• npm
• optional Redis server

Configuration

Copy .env.example to .env and adjust:

cp .env.example .env

Install

npm install

Generate Tools from OpenAPI YAML

Run from local spec:

npx tsx generate.ts

Or from remote URL:

npx tsx generate.ts https://api.openarchieven.nl/openapi.yaml

Expected result:

Generated 21 toolsOutput: generated/tools.json, generated/spec.json

Creates:

generated/tools.jsongenerated/spec.json

Start Server

npx tsx server.ts

Expected startup (development — pretty-printed):

[12:00:00] INFO: Open Archieven MCP server started    port: 3001    tools: 21    upstream: "https://api.openarchieven.nl/1.1"    rateLimit: "4 req/s"    redis: "redis://localhost:6379/5"    env: "development"

In production (NODE_ENV=production) each log line is a single JSON object.

Server binds to:

http://0.0.0.0:3001

Test All Features

1. Health Check

curl http://localhost:3001/health

Expected:

{  "ok": true,  "tools": 21,  "redis": false,  "uptime": 1.23}

2. List Tools

curl http://localhost:3001/tools

Expected:

[  "search_records",  "show_record",  "match_record",  "get_births_years_ago",  "get_births",  "get_deaths",  "get_marriages",  "get_archives",  "get_record_stats",  "get_source_type_stats",  "get_event_type_stats",  "get_comment_stats",  "get_family_name_stats",  "get_first_name_stats",  "get_profession_stats",  "get_historical_weather",  "get_census_data",  "search_transcriptions",  "browse_transcriptions",  "show_transcription"]

3. Tool Call

curl -X POST http://localhost:3001/tools/search_records \-H "Content-Type: application/json" \-d '{"name":"Coret"}'

4. Show a Single Record

curl -X POST http://localhost:3001/tools/show_record \-H "Content-Type: application/json" \-d '{"archive":"hua","identifier":"E13B9821-C0B0-4AED-B20B-8DE627ED99BD"}'

5. SSE Streaming

curl -N "http://localhost:3001/events/search_records?name=Coret"

Expected stream:

event: pagedata: {...}
event: pagedata: {...}
event: donedata: {}

6. Heartbeat Test

Leave SSE open for 15+ seconds — expect periodic keep-alive lines:

: heartbeat

7. Chunked HTTP Streaming

curl -N -X POST http://localhost:3001/stream/search_records \-H "Content-Type: application/json" \-d '{"name":"Coret"}'

Expected (newline-delimited JSON):

{"query":{...},"response":{"number_found":...,"docs":[...]}}{"query":{...},"response":{"number_found":...,"docs":[...]}}

8. MCP Initialize

curl -X POST http://localhost:3001/ \-H "Content-Type: application/json" \-H "Accept: application/json, text/event-stream" \-d '{  "jsonrpc": "2.0",  "id": 1,  "method": "initialize",  "params": {    "protocolVersion": "2025-03-26",    "capabilities": {},    "clientInfo": { "name": "test", "version": "1.0" }  }}'

9. MCP List Tools

curl -X POST http://localhost:3001/ \-H "Content-Type: application/json" \-H "Accept: application/json, text/event-stream" \-d '{  "jsonrpc": "2.0",  "id": 2,  "method": "tools/list"}'

10. MCP Call Tool

curl -X POST http://localhost:3001/ \-H "Content-Type: application/json" \-H "Accept: application/json, text/event-stream" \-d '{  "jsonrpc": "2.0",  "id": 3,  "method": "tools/call",  "params": {    "name": "search_records",    "arguments": { "name": "Coret" }  }}'

Redis Testing

Start Redis

redis-server

Restart the MCP server. Expected in /health:

{ "redis": true }

Without Redis

Stop Redis and restart. Expected:

{ "redis": false }

Common Commands

Regenerate after API changes

npx tsx generate.ts

Restart server

npx tsx server.ts

Run tests

npm test

Tests cover the per-tool TTL strategy (cache-ttl.ts) using Node's built-in test runner — no extra dependencies. The coverage test asserts every tool emitted by generate.ts has an explicit TTL entry, so re-running npm run generate after an upstream OpenAPI change will surface any new tool that needs a TTL decision.

Troubleshooting

Generated files missing

npx tsx generate.ts

Port already in use

Linux / macOS:

lsof -i :3001kill -9 <PID>

Windows:

netstat -ano | findstr :3001taskkill /PID <PID> /F

Redis not connecting

Server runs normally without Redis. Check REDIS_URL in .env.

Rate limit errors (429)

The upstream API allows 4 req/s per IP. The built-in rate limiter queues requests automatically. If you are running multiple server instances, reduce RATE_LIMIT_RPS or use a shared queue.

Privacy Policy

This server is a thin proxy over the public Open Archives API. It does not require user authentication and does not collect personal data of its own.

The full privacy policies of the operators apply in addition to this section:

• Open Archives — Disclaimer & Privacy
• Coret Genealogy — Privacy Policy

Data collection

• Tool arguments (e.g. a search name, an archive code, a record identifier) are received from the MCP client.
• HTTP request metadata — method, path, status code, latency, and the source IP — is observed by the reverse proxy in front of the hosted endpoint at mcp.openarchieven.nl.
• No accounts, cookies, tokens, or session identifiers are collected. The server is anonymous-by-design.

Use and storage

• Tool arguments are forwarded verbatim over HTTPS to https://api.openarchieven.nl/1.1 to fulfill the request, and the upstream response is returned to the caller.
• Application logs (tool name, arguments, status, latency) are written to stdout via pino. On the hosted endpoint these logs are ephemeral: they are not written to disk and are lost on process restart. Set LOG_LEVEL=warn to suppress argument logging.
• Cache (optional): when Redis is configured, upstream responses are cached under keys of the form mcp:<tool>:<sorted-params-json>. The cache contains response bodies only; no user identifiers are stored.

Third-party sharing

No data is sent to any service other than the upstream Open Archives API listed above. There are no analytics, telemetry, advertising, or observability third parties involved.

Data retention

Security

The MCP endpoint validates the Origin header on every request and rejects unknown browser origins (DNS-rebinding defense). All transport is over HTTPS.

External links surfaced to clients

Tool responses include URLs that point to record pages on https://www.openarchieven.nl. The submission declares the following allowed link URI so users are not prompted to confirm each link:

• https://www.openarchieven.nl

Contact

For privacy questions or requests, contact:

• Email: [email protected]
• GitHub: open an issue

Recommended Production Upgrades

• HTTPS reverse proxy (nginx / caddy)
• PM2 or systemd process manager
• Structured JSON logging (pino / winston)
• Request tracing (OpenTelemetry)
• Auth middleware if server is public-facing
• Shared Redis for multi-instance deployments

Version

v1.0

Schema-perfect OpenAPI-generated MCP server for Open Archives.