chembl-mcp-server

v0.2.0 pre-1.0

Link compounds to protein targets, rank bioactivity (IC50/Ki/EC50), and look up drug mechanisms and indications over ChEMBL via MCP. STDIO or Streamable HTTP.

chembl.caseyjhand.com/mcp
claude mcp add --transport http chembl-mcp-server https://chembl.caseyjhand.com/mcp
codex mcp add chembl-mcp-server --url https://chembl.caseyjhand.com/mcp
{
  "mcpServers": {
    "chembl-mcp-server": {
      "url": "https://chembl.caseyjhand.com/mcp"
    }
  }
}
gemini mcp add --transport http chembl-mcp-server https://chembl.caseyjhand.com/mcp
{
  "mcpServers": {
    "chembl-mcp-server": {
      "command": "bunx",
      "args": [
        "mcp-remote",
        "https://chembl.caseyjhand.com/mcp"
      ]
    }
  }
}
{
  "mcpServers": {
    "chembl-mcp-server": {
      "type": "http",
      "url": "https://chembl.caseyjhand.com/mcp"
    }
  }
}
curl -X POST https://chembl.caseyjhand.com/mcp \
  -H "Content-Type: application/json" \
  -H "MCP-Protocol-Version: 2025-11-25" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{},"clientInfo":{"name":"curl","version":"1.0.0"}}}'

Tools

7

chembl_search_molecules

open-world

Discovery entry point for compounds. Find by name / ChEMBL ID / InChIKey with the default search_type=name (supply query), or run a structure search with search_type exact | similarity | substructure (supply structure as a SMILES). At least one of query or structure is required, and structure is required for the three structure modes. Returns ChEMBL ID, preferred name, canonical SMILES, formula, MW, AlogP, Lipinski violations, QED, and max clinical phase on every row; structure searches also carry a Tanimoto similarity percent. Chain molecule_chembl_id into chembl_get_bioactivities or chembl_get_drug_info.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_search_molecules",
    "arguments": {}
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "query": {
      "description": "Search text for search_type=name — a drug name, ChEMBL ID, or InChIKey, e.g. \"imatinib\" or \"CHEMBL25\".",
      "type": "string"
    },
    "structure": {
      "description": "SMILES string for structure search, e.g. \"CC(=O)Oc1ccccc1C(=O)O\". Required when search_type is exact/similarity/substructure.",
      "type": "string"
    },
    "search_type": {
      "default": "name",
      "description": "name = text lookup (query); exact = exact structure match; similarity = Tanimoto ≥ threshold; substructure = contains the structure. All structure modes need `structure`.",
      "type": "string",
      "enum": [
        "name",
        "exact",
        "similarity",
        "substructure"
      ]
    },
    "similarity_threshold": {
      "default": 70,
      "description": "Minimum Tanimoto similarity percent for search_type=similarity (40–100; ChEMBL rejects below 40). Ignored for other modes.",
      "type": "integer",
      "minimum": 40,
      "maximum": 100
    },
    "max_phase_min": {
      "description": "For search_type=name, restrict to compounds at or above this max clinical phase (e.g. 4 for marketed drugs only).",
      "type": "integer",
      "minimum": 0,
      "maximum": 4
    },
    "limit": {
      "description": "Maximum molecules to return. Defaults to the server default (25) when omitted.",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    }
  },
  "required": [
    "search_type",
    "similarity_threshold"
  ],
  "additionalProperties": false
}
view source ↗

chembl_get_bioactivities

open-world

The flagship compound↔target bioactivity bridge: measurements for a molecule (target deconvolution / selectivity) OR a target (lead finding). Supply exactly one of molecule_chembl_id (from chembl_search_molecules) or target_chembl_id (from chembl_search_targets) — both or neither is an error. Filter by standard_type (IC50/Ki/EC50/…), minimum potency pchembl_value_min, assay_type, and organism. Rows are ranked by potency: the preview surfaces measurements with a derivable pchembl_value (ChEMBL sorts the null-potency rows first otherwise), while totalCount stays the honest full match count including measurements without one. Mixing measurement types (IC50 vs Ki) is a scientific error — set standard_type to compare like with like. A popular target carries tens of thousands of rows: results spill to a DataCanvas table (bioactivities) you SQL with chembl_dataframe_query for honest aggregates across the staged set, while an inline preview answers the immediate question. Spilling requires CANVAS_PROVIDER_TYPE=duckdb; otherwise the inline rows are capped at limit (a preview, not the full set).

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_get_bioactivities",
    "arguments": {}
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "molecule_chembl_id": {
      "description": "ChEMBL molecule ID (from chembl_search_molecules), e.g. \"CHEMBL941\". Supply this XOR target_chembl_id.",
      "type": "string"
    },
    "target_chembl_id": {
      "description": "ChEMBL target ID (from chembl_search_targets), e.g. \"CHEMBL203\". Supply this XOR molecule_chembl_id.",
      "type": "string"
    },
    "standard_type": {
      "description": "Restrict to one measurement type, e.g. \"IC50\", \"Ki\", \"EC50\". Set this to compare potencies validly.",
      "type": "string"
    },
    "pchembl_value_min": {
      "description": "Minimum pchembl_value (−log10 molar potency), e.g. 7 keeps sub-100 nM activities.",
      "type": "number"
    },
    "assay_type": {
      "description": "Restrict to an assay type code: \"B\" (binding), \"F\" (functional), \"A\" (ADMET), \"T\" (toxicity).",
      "type": "string"
    },
    "organism": {
      "description": "Restrict to a target organism, e.g. \"Homo sapiens\" (case-insensitive exact match).",
      "type": "string"
    },
    "limit": {
      "description": "Maximum rows in the inline preview. Defaults to the server default (25). The full set still spills to the canvas.",
      "type": "integer",
      "minimum": 1,
      "maximum": 1000
    },
    "canvas_id": {
      "description": "Optional canvas ID from a prior call to reuse the same canvas. The bioactivities table is re-staged, so a second query REPLACES (overwrites) the prior rows on that canvas — it does not append. Omit to mint a fresh canvas.",
      "type": "string"
    }
  },
  "additionalProperties": false
}
view source ↗

chembl_search_targets

open-world

Resolve a protein/gene/UniProt accession to the ChEMBL target ID that chembl_get_bioactivities needs for the target→leads workflow. Supply at least one of accession (UniProt, e.g. P00533), gene_symbol (e.g. EGFR), or query (free-text name); filter further by organism and target_type. Returns each target with its type, organism, and component UniProt accessions + gene symbols. A UniProt accession from the uniprot/protein server is the most precise input.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_search_targets",
    "arguments": {}
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "query": {
      "description": "Free-text name match against the target preferred name, e.g. \"kinase\" or \"growth factor receptor\".",
      "type": "string"
    },
    "accession": {
      "description": "UniProt accession of a target component, e.g. \"P00533\". The most precise resolver — from the uniprot/protein server.",
      "type": "string"
    },
    "gene_symbol": {
      "description": "Gene symbol of a target component, e.g. \"EGFR\" (case-insensitive exact match).",
      "type": "string"
    },
    "organism": {
      "description": "Restrict to a source organism, e.g. \"Homo sapiens\" (case-insensitive exact match).",
      "type": "string"
    },
    "target_type": {
      "description": "Restrict to a target class, e.g. \"SINGLE PROTEIN\" or \"PROTEIN COMPLEX\".",
      "type": "string"
    },
    "limit": {
      "description": "Maximum targets to return. Defaults to the server default (25) when omitted.",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    }
  },
  "additionalProperties": false
}
view source ↗

chembl_get_drug_info

open-world

Pharmacology for a drug (molecule): mechanism(s) of action, the molecular target(s) it acts on, action type (inhibitor / agonist / …), first-approval year, and clinical indications with the max phase reached for each. Supply molecule_chembl_id (from chembl_search_molecules). Distinct from the openfda server's label/adverse-event view — this is the curated mechanism-and-indication record. A mechanism's target_chembl_id chains into chembl_get_bioactivities for compounds hitting the same target.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_get_drug_info",
    "arguments": {
      "molecule_chembl_id": "<molecule_chembl_id>"
    }
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "molecule_chembl_id": {
      "type": "string",
      "minLength": 1,
      "description": "ChEMBL molecule ID (from chembl_search_molecules), e.g. \"CHEMBL939\" for gefitinib."
    }
  },
  "required": [
    "molecule_chembl_id"
  ],
  "additionalProperties": false
}
view source ↗

chembl_get_assay

open-world

Assay provenance behind a bioactivity row: description, type (binding / functional / ADMET / toxicity), the target it measures, organism, and ChEMBL's 1–9 confidence score (9 = direct assay on the protein target, lower = homologous or indirect). Supply assay_chembl_id from a chembl_get_bioactivities row. Call this to judge whether two measurements are comparable before ranking them together.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_get_assay",
    "arguments": {
      "assay_chembl_id": "<assay_chembl_id>"
    }
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "assay_chembl_id": {
      "type": "string",
      "minLength": 1,
      "description": "ChEMBL assay ID from a bioactivity row's assay_chembl_id, e.g. \"CHEMBL674637\"."
    }
  },
  "required": [
    "assay_chembl_id"
  ],
  "additionalProperties": false
}
view source ↗

chembl_dataframe_query

Run a read-only SQL SELECT over the bioactivity rows chembl_get_bioactivities spilled to a canvas — rank, group, dedupe, and aggregate across the FULL set, not the inline preview. Reference the staged table by the name chembl_get_bioactivities returned (bioactivities); discover columns with chembl_dataframe_describe. Compute honest aggregates here (e.g. SELECT molecule_chembl_id, MEDIAN(pchembl_value) AS med FROM bioactivities WHERE standard_type = 'IC50' GROUP BY 1 ORDER BY 2 DESC). Returns up to the canvas row cap; truncated is true when the SQL result exceeds that cap. Requires CANVAS_PROVIDER_TYPE=duckdb.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_dataframe_query",
    "arguments": {
      "canvas_id": "<canvas_id>",
      "sql": "<sql>"
    }
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "canvas_id": {
      "type": "string",
      "description": "Canvas ID returned by chembl_get_bioactivities (spilled: true)."
    },
    "sql": {
      "type": "string",
      "description": "A read-only SELECT against the staged tables. Reference tables by the names chembl_get_bioactivities returned."
    }
  },
  "required": [
    "canvas_id",
    "sql"
  ],
  "additionalProperties": false
}
view source ↗

chembl_dataframe_describe

List the tables and columns staged on a canvas by chembl_get_bioactivities — inspect before calling chembl_dataframe_query to write correct SQL. Returns each table with its row count, kind (table | view), and column names + types. Requires CANVAS_PROVIDER_TYPE=duckdb.

read
invocation
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chembl_dataframe_describe",
    "arguments": {
      "canvas_id": "<canvas_id>"
    }
  }
}
schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "canvas_id": {
      "type": "string",
      "description": "Canvas ID returned by chembl_get_bioactivities (spilled: true)."
    }
  },
  "required": [
    "canvas_id"
  ],
  "additionalProperties": false
}
view source ↗

Resources

2

A molecule record by ChEMBL ID — the same shape a chembl_search_molecules row carries (ID, names, structures, properties, max clinical phase). Convenience injectable-context mirror of the per-molecule fetch.

uri chembl://molecule/{chemblId} mime application/json

A target record by ChEMBL target ID — pref_name, type, organism, and component UniProt accessions + gene symbols. Convenience injectable-context mirror of the per-target fetch.

uri chembl://target/{chemblId} mime application/json