ClinicalTrials.gov MCP Server (cyanheads)

Community-maintained MCP server wrapping the ClinicalTrials.gov v2 API. Supports full-text trial search, complete study retrieval by NCT ID, extraction of outcomes / adverse events / participant flow from completed studies, and patient-to-trial matching against current recruiting trials.

   
Type MCP server
Supplier cyanheads (Casey Hand)
Availability GA — distributed on npm as clinicaltrialsgov-mcp-server
Pricing Free / OSS (Apache-2.0). No API key required; public hosted instance hosted on Cloudflare Workers free tier.
Capabilities Read-only — ClinicalTrials.gov API queries; optional patient-matching tool

How to install

  • Also packaged in the SciAgent-Skills collection (jaechang-hits (community OSS, CC BY 4.0)): clone jaechang-hits/SciAgent-Skills and run /plugin install sciagent-skills in Claude Code (or copy skills/structural-biology-drug-discovery/clinicaltrials-database-search into ~/.claude/skills/).

  • Claude Code — point at the hosted public instance (zero install):

    claude mcp add --transport http clinicaltrials https://clinicaltrials.caseyjhand.com/mcp

  • Claude Code — local stdio via npx:

    claude mcp add-json clinicaltrialsgov-mcp-server '{"command":"npx","args":["-y","clinicaltrialsgov-mcp-server@latest"],"env":{"MCP_LOG_LEVEL":"info"}}'

  • Claude Desktop — add to claude_desktop_config.json:

    {
  "mcpServers": {
    "clinicaltrialsgov-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["clinicaltrialsgov-mcp-server@latest"],
      "env": { "MCP_TRANSPORT_TYPE": "stdio" }
    }
  }
}

    Or, to use the hosted endpoint from Claude Desktop (no native HTTP transport), proxy via mcp-remote:

    {
  "mcpServers": {
    "clinicaltrials": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://clinicaltrials.caseyjhand.com/mcp"]
    }
  }
}

What it does

  • search_studies — full-text search across studies with filters, pagination, sorting, and field selection.
  • get_study — full record by NCT ID: protocol, eligibility, outcomes, arms, interventions, contacts, locations.
  • get_study_results — outcomes, adverse events, participant flow, and baseline data from completed studies; optional summary mode reduces a ~200KB payload to ~5KB.
  • match_patient — match patient demographics and conditions to eligible recruiting trials.

Primary use cases: Trial-eligibility screening, competitive landscaping for protocol drafting, adverse-event review across completed trials, patient-trial matching at point of care, and meta-analysis sourcing.

Notes

The server works with defaults and no API keys. The hosted instance is convenient for evaluation; for production or PHI-adjacent workflows, self-host (local stdio or Cloudflare Workers deploy supported). Pluggable auth modes — none, jwt, oauth — are documented in the repo.

Sources

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