clinicaltrialsgov-mcp-server
Search ClinicalTrials.gov trials, retrieve study details and results, and match patients to eligible trials via MCP. STDIO or Streamable HTTP.
7 Tools • 1 Resource • 1 Prompt
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**Public Hosted Server:** [https://clinicaltrials.caseyjhand.com/mcp](https://clinicaltrials.caseyjhand.com/mcp)
---
## Overview
Seven tools for searching, discovering, analyzing, and matching clinical trials:
| Tool Name | Description |
| :------------------------------------- | :----------------------------------------------------------------------------------------------- |
| `clinicaltrials_search_studies` | Search studies with full-text queries, filters, pagination, sorting, and field selection. |
| `clinicaltrials_get_study_record` | Fetch a single study by NCT ID. Returns the full record: protocol, eligibility, outcomes, arms, interventions, contacts, and locations. |
| `clinicaltrials_get_study_count` | Get total study count for a query without fetching data. Fast statistics and breakdowns. |
| `clinicaltrials_get_field_values` | Discover valid values for API fields (status, phase, study type, etc.) with per-value counts. |
| `clinicaltrials_get_field_definitions` | Browse the study data model field tree — piece names, types, nesting. Supports subtree navigation and keyword search. |
| `clinicaltrials_get_study_results` | Extract outcomes, adverse events, participant flow, and baseline from completed studies. Optional summary mode reduces ~200KB payloads to ~5KB. |
| `clinicaltrials_find_eligible` | Match patient demographics and conditions to eligible recruiting trials. Provide age, sex, conditions, and location to find studies with matching eligibility criteria, contacts, and recruiting locations. |
| Resource | Description |
| :------------------------- | :-------------------------------------------------- |
| `clinicaltrials://{nctId}` | Fetch a single clinical trial study by NCT ID. Full JSON. |
| Prompt | Description |
| :------------------------ | :--------------------------------------------------------------------------------- |
| `analyze_trial_landscape` | Adaptable workflow for data-driven trial landscape analysis using count + search tools. |
## Tools
### `clinicaltrials_search_studies`
Primary search tool with full ClinicalTrials.gov query capabilities.
- Full-text and field-specific queries (condition, intervention, sponsor, location, title, outcome)
- Status and phase filters with typed enum values
- Geographic proximity filtering by coordinates and distance
- Advanced AREA[] Essie expression support for complex queries
- Compact index results by default; pass `fields` for a full-fidelity projection of specific leaves (a full single record is ~70KB — fetch one with `get_study_record`)
- Pagination with cursor tokens, sorting by any field
---
### `clinicaltrials_get_study_results`
Fetch posted results data for completed studies.
- Outcome measures with statistics, adverse events, participant flow, baseline characteristics
- Section-level filtering (request only the data you need)
- Optional summary mode condenses full results (~200KB) to essential metadata (~5KB per study)
- Batch multiple NCT IDs per call with partial-success reporting
- Separate tracking of studies without results and fetch errors
---
### `clinicaltrials_find_eligible`
Match a patient profile to eligible recruiting trials.
- Takes age, sex, conditions, and location as patient demographics
- Builds optimized API queries with demographic filters (age range, sex, healthy volunteers)
- Re-ranks results so studies whose own condition matches a requested condition surface above tangential matches from the upstream fuzzy condition search
- Returns studies with eligibility and location fields for the caller to evaluate
- Provides actionable hints when no studies match (broaden conditions, adjust filters)
## Features
Built on [`@cyanheads/mcp-ts-core`](https://github.com/cyanheads/mcp-ts-core):
- Declarative tool/resource/prompt definitions with Zod schemas and format functions
- Unified error handling — handlers throw, framework catches and classifies
- Dual transport: stdio and Streamable HTTP from the same codebase
- Pluggable auth (`none`, `jwt`, `oauth`) for HTTP transport
- Structured logging with optional OpenTelemetry tracing
ClinicalTrials.gov-specific:
- Type-safe client for the [ClinicalTrials.gov REST API v2](https://clinicaltrials.gov/data-api/api)
- Public API — no authentication or API keys required
- Retry with exponential backoff (3 attempts) and rate limiting (~1 req/sec)
- HTML error detection and structured error factories
## Getting Started
### Public Hosted Instance
A public instance is available at `https://clinicaltrials.caseyjhand.com/mcp` — no installation required. Point any MCP client at it via Streamable HTTP:
```json
{
"mcpServers": {
"clinicaltrialsgov-mcp-server": {
"type": "streamable-http",
"url": "https://clinicaltrials.caseyjhand.com/mcp"
}
}
}
```
### Self-Hosted / Local
Add to your MCP client config (e.g., `claude_desktop_config.json`):
```json
{
"mcpServers": {
"clinicaltrialsgov-mcp-server": {
"type": "stdio",
"command": "bunx",
"args": ["clinicaltrialsgov-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio"
}
}
}
}
```
Or for Streamable HTTP:
```sh
MCP_TRANSPORT_TYPE=http
MCP_HTTP_PORT=3010
```
### Prerequisites
- [Bun v1.3.0](https://bun.sh/) or higher (or Node.js >= 24.0.0)
### Installation
1. **Clone the repository:**
```sh
git clone https://github.com/cyanheads/clinicaltrialsgov-mcp-server.git
```
2. **Navigate into the directory:**
```sh
cd clinicaltrialsgov-mcp-server
```
3. **Install dependencies:**
```sh
bun install
```
## Configuration
All configuration is optional — the server works with defaults and no API keys.
| Variable | Description | Default |
| :--------------------------- | :------------------------------------------ | :---------------------------------- |
| `CT_API_BASE_URL` | ClinicalTrials.gov API base URL. | `https://clinicaltrials.gov/api/v2` |
| `CT_REQUEST_TIMEOUT_MS` | Per-request timeout in milliseconds. | `30000` |
| `CT_MAX_PAGE_SIZE` | Maximum page size cap. | `200` |
| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http`. | `stdio` |
| `MCP_HTTP_PORT` | Port for HTTP server. | `3010` |
| `MCP_AUTH_MODE` | Auth mode: `none`, `jwt`, or `oauth`. | `none` |
| `MCP_LOG_LEVEL` | Log level (RFC 5424). | `info` |
| `LOGS_DIR` | Directory for log files (Node.js only). | `/logs` |
| `OTEL_ENABLED` | Enable OpenTelemetry tracing. | `false` |
## Running the Server
### Local Development
- **Build and run the production version:**
```sh
bun run build
bun run start:http # or start:stdio
```
- **Run checks and tests:**
```sh
bun run devcheck # Lints, formats, type-checks
bun run test # Runs test suite
```
### Docker
```sh
docker build -t clinicaltrialsgov-mcp-server .
docker run -p 3010:3010 clinicaltrialsgov-mcp-server
```
## Project Structure
| Directory | Purpose |
| :------------------------------ | :---------------------------------------------------- |
| `src/mcp-server/tools/` | Tool definitions (`*.tool.ts`). |
| `src/mcp-server/resources/` | Resource definitions (`*.resource.ts`). |
| `src/mcp-server/prompts/` | Prompt definitions (`*.prompt.ts`). |
| `src/services/clinical-trials/` | ClinicalTrials.gov API client and types. |
| `src/config/` | Environment variable parsing and validation with Zod. |
| `tests/` | Unit and integration tests. |
## Development Guide
See [`CLAUDE.md`](./CLAUDE.md) for development guidelines and architectural rules. The short version:
- Handlers throw, framework catches — no `try/catch` in tool logic
- Use `ctx.log` for request-scoped logging, no `console` calls
- Register new tools and resources in the `index.ts` barrel files
## Contributing
Issues and pull requests are welcome. Run checks before submitting:
```sh
bun run devcheck
bun run test
```
## License
Apache-2.0 — see [LICENSE](LICENSE) for details.