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Cern Opendata MCP Server

answering

Cern Opendata MCP Server is answering right now. Last checked 14 min ago. 123 installs a week from npm. It exposes 7 tools. Last commit 30 Oct 2026.

Search CERN Open Data, fetch records, files, analysis environments, CMS good-run lists, HLT paths.

Installs per day peak 353 · avg 37 · -51% w/w
a month agotoday
Uptime history 31 days of history · worst day 98%
31 days agonow
100.0%
Uptime 24h
91 of 91 checks
7
Tools
read from the server
551 ms
Response time
average over 24h
123
Installs / week
npm and PyPI

What changed 11

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 18 October 2026. No other catalogue keeps this.

30 Oct a tool changed the parameters it asks for cern_opendata_search_records
30 Oct a tool changed version
18 Oct 6 tools changed the parameters they ask for cern_opendata_get_analysis_env, cern_opendata_get_records, cern_opendata_get_validated_runs and 3 more
18 Oct 2 tool descriptions were rewritten cern_opendata_get_records, cern_opendata_search_trigger_paths
18 Oct a tool changed version

Nothing serious here today

Today is the operative word: we check Cern Opendata MCP Server every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 14 min ago.

run in your terminal
claude mcp add cern-opendata-mcp-server --transport http https://cern-opendata.caseyjhand.com/mcp
Settings → Connectors → Add custom connector, then paste this address
https://cern-opendata.caseyjhand.com/mcp
~/.codex/config.toml
[mcp_servers.cern-opendata-mcp-server]
url = "https://cern-opendata.caseyjhand.com/mcp"
.cursor/mcp.json
{
  "mcpServers": {
    "cern-opendata-mcp-server": {
      "url": "https://cern-opendata.caseyjhand.com/mcp"
    }
  }
}
.vscode/mcp.json
{
  "servers": {
    "cern-opendata-mcp-server": {
      "type": "http",
      "url": "https://cern-opendata.caseyjhand.com/mcp"
    }
  }
}

Available tools 7

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

cern
cern_opendata_get_analysis_env
Assemble what is needed to analyse a record: its container images, CMSSW release and global tag; the condition-data, VM and validated-run records for its run periods; example software that declares it works with the record; and quoted sections of the guides the record links (the first two are fetched). Container images, software and guide code are licensed separately from the CC0 data. Use cern_opendata_list_files for the record's files.
cern_opendata_get_records
Fetch full metadata for 1-20 records in one call, by recid, DOI, CMS dataset path (/Primary/Era/TIER) or documentation slug. Returns the description, run periods, collision and distribution details, related records, a software-environment summary, the license and a ready citation, plus what a record states of its variable dictionary, physics category, pile-up, keywords, and LHCb magnet polarity and stripping. Documentation and news pages include their markdown body in slices of at most 30,000 characters; body_offset with that one id reads on from where a slice stops. Each response holds to 64,000 bytes, except that the first record always comes back whole: records past the budget, and ids past the first 20, are listed under deferred, to pass back as ids. File lists are not included; use cern_opendata_list_files. Identifiers that do not resolve come back under missing with guidance; they do not fail the call.
cern_opendata_get_validated_runs
Get a CMS validated-run (good-run) list, which certifies the luminosity sections that are good for physics in each run. Select it by a CMS collision dataset recid, a validated-run list recid, or a run period such as Run2012B (give exactly one of recid and run_period). Choose the full validation or the muons-only variant, and narrow to a run range; a dataset recid defaults the range to the first and last run the dataset lists. Returns the runs with their luminosity-section ranges and the list file download URL. CMS only.
cern_opendata_list_files
List one record's files: its file indexes (groups of up to ~1,500 files) with their XRootD URI-list URLs, and per file the XRootD URI, HTTPS download URL, size, adler32 checksum and availability. Without index, returns the record's indexes and its regular files; with index, reads only that index and pages through its files. Files marked on demand sit on tape and must be requested on the record's portal page before download.
cern_opendata_list_reference
Decode the vocabulary the other cern_opendata tools accept: experiments, record types, collision energies and types, file formats and data tiers, availability states, physics categories, LHCb magnet polarities and stripping streams and versions, identifier forms, query syntax, licensing, and the CMS run periods that have validated-run lists. Static and offline; omit topic for every table.
cern_opendata_search_records
Search the CERN Open Data Portal's datasets, software, environments, documentation and supplementary records with exact-vocabulary filters and an optional full-text query. The filters are experiment, record type, physics category, keyword, collision energy and type, file format, data-taking year, event count, availability, collection, and LHCb magnet polarity, stripping stream and stripping version. Returns compact hits with recids plus live facet counts. Each facet ignores its own filter, so its counts show the alternatives under the other filters. Filter values are exact upstream; common spellings are normalized, and cern_opendata_list_reference lists the vocabulary. Paging reaches the first 10,000 matches.
cern_opendata_search_trigger_paths
Look up CMS High-Level Trigger paths by exact name (HLT_IsoMu24) or prefix pattern (HLT_IsoMu*), optionally for one data-taking year. Paths outside the HLT_ family, such as AlCa_EcalPi0, DST_ and DQM_ paths, output modules and HLTriggerFinalPath, are found by their own names, in the case given. Each match is a per-year path record parsed into the primary datasets its title names, the first and last run the path was seen online, per-version run ranges, the L1 seed, and links to the HLT menu records. Covers CMS open data from 2011-2016. Prescale factors are not returned: each HLT menu record holds a configuration file (cern_opendata_list_files with a menu_recid) whose PrescaleService block lists the prescale in each column of every path it prescales (a path it leaves out has prescale 1), and the CMS luminosity records (collection CMS-Luminosity-Information) hold prescale files that log which column applied by run and luminosity section.

Endpoints

URLTransportStateLatencyChecked
https://cern-opendata.caseyjhand.com/mcp streamable-http answering 533 ms 14 min ago

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Cern Opendata MCP Server — questions

Answers built from our own checks of this server.

What can Cern Opendata MCP Server do?
It exposes 7 tools, read directly from the server on our last check. Among them: cern_opendata_get_analysis_env, cern_opendata_get_records, cern_opendata_get_validated_runs, cern_opendata_list_files, cern_opendata_list_reference, cern_opendata_search_records and 1 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →
Is Cern Opendata MCP Server working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 551 ms. The bar chart above shows every period we have measured.
How do I connect Cern Opendata MCP Server?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does Cern Opendata MCP Server need an API key?
No. Cern Opendata MCP Server completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 7 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is Cern Opendata MCP Server?
It answers our handshake in 551 ms on average, which is faster than 21% of all working MCP servers we measure. That is on the slow side — worth knowing if the tool sits inside an interactive loop. The comparison comes from our own checks across the whole registry, every 15 minutes.
How many people use Cern Opendata MCP Server?
The npm package @cyanheads/cern-opendata-mcp-server was installed 123 times in the last week. Week over week that is -51%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.
Is Cern Opendata MCP Server open source?
The code is open source: it is published under the Apache-2.0 licence, written in TypeScript, 1 stars on GitHub and 3 open issues. The licence covers the code in the repository, not the hosted service at cern-opendata.caseyjhand.com, which runs on its operator's own terms.