Claude Desktop
Desktop · Freemium · Proprietary
Anthropic's official Claude AI desktop application. Supports MCP servers to extend functionality.
WindowsMacOS
Research & Data · Developer Tools
Clinicaltrialsgov MCP Server
cyanheads/clinicaltrialsgov-mcp-server
Search ClinicalTrials.gov trials, retrieve study details and results, and match patients to eligible trials via MCP. STDIO or Streamable HTTP.
Install
bunx clinicaltrialsgov-mcp-server@latestClient configuration
{
"mcpServers": {
"clinicaltrialsgov-mcp-server": {
"command": "bunx",
"args": [
"clinicaltrialsgov-mcp-server@latest"
],
"env": {
"MCP_TRANSPORT_TYPE": "<MCP_TRANSPORT_TYPE>",
"MCP_LOG_LEVEL": "<MCP_LOG_LEVEL>"
}
}
}
}Environment variables
MCP_TRANSPORT_TYPEMCP_LOG_LEVEL- Author
- @cyanheads
- Category
- Research & Data, Developer Tools
- License
- Apache-2.0
- Updated
- Oct 6, 2026
Features
Type-safe client for the ClinicalTrials.gov REST API v2 — public, no authentication or API keys required
Serialized request queue enforcing ClinicalTrials.gov's ~1 req/sec rate limit, with retry and exponential backoff on 429/5xx responses
Auto-corrects field names passed to fields/sort — case/whitespace fixes and known legacy aliases (e.g. RecruitmentStatus → OverallStatus) — before validating, logging every correction
Detects upstream HTML error pages returned with a JSON content-type and retries rather than parsing them as data
Geographic proximity search and nearest-site re-ranking, with no geocoding dependency
Excludes ClinicalTrials.gov's "unknown" enrollment sentinel (99999999) from searches and counts by default — includeUnknownEnrollment brings it back, and an nctIds lookup never filters it
Provenance — clinicaltrials_search_studies / clinicaltrials_get_study_count / clinicaltrials_find_eligible echo searchCriteria on every call, including sentinelFilterActive when the default…
Graceful partial failure — clinicaltrials_get_study_results returns per-study fetchErrors / studiesWithoutResults rows instead of failing the whole batch when one ID is malformed or lacks results
Discriminated output — typed error reason codes per tool (study_not_found, blank_value, offset_not_applicable, …), and bounded lists (filtersApplied, locationSummary) carry a next*Offset only when…
Response shaping — clinicaltrials_search_studies and clinicaltrials_find_eligible return a compact per-study index or location-bounded set by default instead of the ~70KB full record, escalating to…
Tools (11)
clinicaltrials_search_studies
Search studies with full-text and field-specific queries, status/phase/geographic filters, pagination, sorting, and field selection
clinicaltrials_get_study_record
Fetch a single study by NCT ID — full protocol record with optional location/outcome/reference caps
clinicaltrials_get_study_count
Fast total study count for a query, without fetching data
clinicaltrials_get_field_values
Discover valid values for API fields, with per-value study counts
clinicaltrials_get_field_definitions
Resolve valid field names — keyword search, path drill-down, or top-level overview
clinicaltrials_get_study_results
Fetch posted results — outcomes, adverse events, participant flow, baseline — for completed studies
clinicaltrials_find_eligible
Match patient demographics and conditions to eligible recruiting trials
filtersApplied
reports upstream totals when a cap trims a list; resultsSection is replaced by resultsSummary counts.
multiValued
flags fields whose per-value counts can sum above the study total.
mode
search (keyword query, limit ≤100, default 20), drill (dot-notation path), or overview — resolves the PascalCase names accepted by fields, advancedFilter,…
age
sex (FEMALE / MALE / ALL), conditions[], location (country required, state / city optional), healthyVolunteer, recruitingOnly (default true), maxResults (≤50),…
Details on this page are taken from the project's README. Open README
Supported clients
Clients mentioned in this server's README:
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