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Pubchem MCP Server

answering

Pubchem MCP Server is answering right now. Last checked 10 min ago. 2 883 installs a week from npm. It exposes 10 tools. Last commit 28 Oct 2026.

Search PubChem compounds, properties, safety data, bioactivity, and cross-references.

Installs per day peak 785 · avg 138 · +1260% w/w
a month agotoday
Uptime history 90 days of history · worst day 0%
90 days agonow
100.0%
Uptime 24h
91 of 91 checks
10
Tools
read from the server
488 ms
Response time
average over 24h
2 883
Installs / week
npm and PyPI

What changed 54

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 22 August 2026. No other catalogue keeps this.

28 Oct 2 tools changed the parameters they ask for pubchem_get_bioactivity, pubchem_search_assays
28 Oct a tool changed version
24 Oct 5 tools changed the parameters they ask for pubchem_get_bioactivity, pubchem_get_compound_interactions, pubchem_get_compound_xrefs and 2 more
24 Oct 4 tool descriptions were rewritten pubchem_get_bioactivity, pubchem_get_compound_interactions, pubchem_get_compound_xrefs and 1 more
24 Oct a tool changed version
15 Oct 10 tools changed the parameters they ask for pubchem_get_bioactivity, pubchem_get_compound_3d_structure, pubchem_get_compound_details and 7 more
15 Oct 6 tool descriptions were rewritten pubchem_get_compound_details, pubchem_get_compound_interactions, pubchem_get_compound_safety and 3 more
15 Oct a tool changed version
7 Oct a tool changed version
25 Sep 8 tools changed the parameters they ask for pubchem_get_bioactivity, pubchem_get_compound_3d_structure, pubchem_get_compound_details and 5 more
and 15 more, back to 22 August 2026

Nothing serious here today

Today is the operative word: we check Pubchem 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 10 min ago.

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

Available tools 10

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

pubchem
pubchem_get_bioactivity
Get a compound's bioactivity profile: which assays tested it, activity outcomes (Active/Inactive/Inconclusive), target identifiers (NCBI Gene ID, UniProt/GenBank accession), quantitative values (IC50, EC50, Ki, etc.), each assay's type (confirmatory, screening, summary, other), and the PubMed IDs it cites. Filter by outcome, a specific molecular target (NCBI Gene ID or protein accession), and/or assay type to focus the profile — e.g. "is this compound active against target T in confirmatory assays?".
pubchem_get_compound_3d_structure
Get a compound's default 3D conformer — atomic coordinates and bonds — for one CID. format="json" (default) returns atoms and bonds parsed into structured fields; format="sdf" returns the raw V2000 SDF text for passthrough to docking, rendering, or conformer tools. Optionally lists alternate conformer IDs. Not every compound has computed 3D coordinates (large molecules, mixtures, and some salts do not).
pubchem_get_compound_details
Get detailed compound information by CID. Returns physicochemical properties (molecular weight, SMILES, InChIKey, XLogP, TPSA, etc.), optionally with a textual description (pharmacology, mechanism, therapeutic use), known synonyms, drug-likeness assessment (Lipinski/Veber rules), and/or pharmacological classification (FDA classes, MeSH classes, ATC codes). Fetches up to 100 CIDs per call; CIDs past that are returned in unprocessed for a follow-up call.
pubchem_get_compound_image
Fetch a 2D structure diagram (PNG image) for a compound by CID.
pubchem_get_compound_interactions
Get a compound's interaction data: drug-food interactions, and the molecular targets its bioassays name — one entry per target as kinds defines it, with its assay counts by outcome and most potent active value, Active targets first, most potent first. Each entry carries its originating source. Results are paged per kind, with the record total and the next offset reported for each. Drug-food coverage is richest for approved drugs; target covers any compound PubChem has assay data for, and pubchem_get_bioactivity lists one target's assays when given the entry's GeneID or accession. Drug-drug interactions (DrugBank) are unavailable while PubChem's SDQ service refuses automated requests: an explicit drug-drug request is reported in failedKinds while the other kinds still return.
pubchem_get_compound_safety
Get GHS (Globally Harmonized System) hazard classification and safety data for one or more compounds by CID. Returns signal word, pictograms, hazard statements (H-codes), and precautionary statements (P-codes) per compound, merged across sources, plus each source's own classification — its signal word, pictograms, H-codes with ECHA notifier agreement percentages, and notification counts — since sources often disagree. Reports ECHA "Not Classified" verdicts as their own status.
pubchem_get_compound_xrefs
Get external database cross-references for a compound: PubMed citations, patent IDs, gene associations, CAS and EC numbers with the number of source records that deposited each, other registry numbers, and taxonomy IDs. Results are paged per type — capped at maxPerType with the total count reported; reach the IDs past a page with offset. PubMed IDs come highest (most recently assigned) first and the other numeric types in ascending order; CAS and EC come most-attested first; the other string IDs keep PubChem's order. A type that fails to load is named in failedTypes while the others still return; the call fails only when a type fails and no type other than ProteinGI (which PubChem no longer serves) loads.
pubchem_get_summary
Get descriptive summaries for PubChem entities by ID. Supports assays (AID), genes (Gene ID), proteins (UniProt accession), and taxonomy (Tax ID). Up to 10 per call; identifiers past that are returned in unprocessed for a follow-up call.
pubchem_search_assays
Find PubChem bioassays associated with a biological target. Search by gene symbol (e.g. "EGFR"), protein name, NCBI Gene ID, or UniProt accession. Returns a page of assay IDs (AIDs) — page past maxResults with offset — which can be explored further with pubchem_get_summary.
pubchem_search_compounds
Search PubChem for chemical compounds by identifier (name, SMILES, InChI, or InChIKey, up to 25 per call), molecular formula in Hill notation, substructure or superstructure containment, 2D Tanimoto similarity, or the compounds a bioassay (AID) found active or tested. Returns a page of CIDs — reach matches past maxResults with offset. Optionally hydrate results with properties to avoid a follow-up pubchem_get_compound_details call.

Endpoints

URLTransportStateLatencyChecked
https://pubchem.caseyjhand.com/mcp streamable-http answering 533 ms 10 min ago

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Pubchem MCP Server — questions

Answers built from our own checks of this server.

What can Pubchem MCP Server do?
It exposes 10 tools, read directly from the server on our last check. Among them: pubchem_get_bioactivity, pubchem_get_compound_3d_structure, pubchem_get_compound_details, pubchem_get_compound_image, pubchem_get_compound_interactions, pubchem_get_compound_safety and 4 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 Pubchem 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 488 ms. The bar chart above shows every period we have measured.
How do I connect Pubchem 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 Pubchem MCP Server need an API key?
No. Pubchem MCP Server completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 10 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is Pubchem MCP Server?
It answers our handshake in 488 ms on average, which is faster than 25% 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 Pubchem MCP Server?
The npm package @cyanheads/pubchem-mcp-server was installed 2 883 times in the last week. Week over week that is +1260%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.
Is Pubchem MCP Server open source?
The code is open source: it is published under the Apache-2.0 licence, written in TypeScript, 12 stars on GitHub and 2 open issues. The licence covers the code in the repository, not the hosted service at pubchem.caseyjhand.com, which runs on its operator's own terms.