Clinical Trial Design MCP Server

clinical-trial-design

A Claude Code plugin and MCP server for end-to-end clinical trial design.

clinical-trial-design helps biostatisticians and clinical trialists design Phase 2 and Phase 3 confirmatory studies through a conversational interface, backed by validated R packages (gsDesign, gsDesign2, graphicalMCP).

v0.0.13 — pre-beta. Nine MCP tools across single-primary endpoint design (binary, continuous, time-to-event under PH and four NPH frameworks), multi-hypothesis design (co-primary, multi-population, graphical multiplicity / Maurer-Bretz), Monte-Carlo verification, and Word/PDF reporting. Reasoning-chain schema with sponsor-confidential redaction. Operational kernel solves accrual ↔ duration ↔ N, plus optional max_n / max_duration feasibility warnings. 288/288 R tests, 18/18 MCP smoke. Published to npm (clinical-trial-design) and the official MCP registry (io.github.wei-ai-lab/clinical-trial-design). Full change history in CHANGELOG.md; API contract in API_STABILITY.md.

What it is

clinical-trial-design has four layers:

Plus an eval harness under eval/ (11 reproducible scenarios × six scoring dimensions × multi-vendor Claude family) and an examples gallery under examples/ (5 published trials reproduced end-to-end).

What clinical-trial-design actually computes

Status

Tool surface

Nine MCP tools — three single-primary design tools, three multi-hypothesis design tools, three meta tools. Same unified result schema across families.

Single-primary design tools (3)

All three accept comparison ∈ {"superiority", "non-inferiority", "equivalence"} (equivalence on fixed-sample binary / continuous only), alpha, power, sided, allocation_ratio, GS parameters (k, timing, sfu, sfl, test.type), an optional operational block, and an optional reasoning_chain array (citation trail with source_type tags).

design_survival adds events_calc ∈ {"schoenfeld" (default), "lachin-foulkes", "freedman"} for PH GS designs and accepts control_hazard_rate (events per patient-year) as an alternative to control_median.

Multi-hypothesis design tools (3)

Meta tools (3)

Operational kernel

Every endpoint design tool accepts an operational block that solves the simple relations accrual_rate × accrual_duration = sample_size_total and total_trial_duration = accrual_duration + follow_up_duration (plus target_events = sample_size_total × cumulative_event_rate(...) for survival, via uniroot over the closed-form pooled exponential-PH event probability — same kernel gsDesign::nSurv uses internally).

Supply any 0–4 of {accrual_rate, accrual_duration, follow_up_duration, total_trial_duration} plus optional caps {max_n, max_duration}. The solver fills in the missing values with an audit trail (given, derived); cap violations surface as structured feasibility_warnings rather than silent over-cap designs.

Quick start

Prerequisites: R ≥ 4.2, Node ≥ 18. No npm install step (the MCP server ships pre-bundled in mcp-server/dist/index.js) and no remotes::install_local step (the launcher sources r-package/ClinicalTrialDesign/R/*.R directly out of the plugin cache).

1. Install CRAN dependencies (one-time)

R -e 'install.packages(c("gsDesign","gsDesign2","graphicalMCP","jsonlite","officer","rmarkdown"))'

The first four are runtime imports; officer and rmarkdown are Suggests: and only needed for design_report(format="docx") / format="pdf".

Tested dependency versions

clinical-trial-design v0.0.13 was developed and tested against the versions below. CRAN's latest is usually fine; pin to these floors only if you hit a version-skew issue.

2. Install the plugin

Method A — slash commands (recommended, inside Claude Code)

/plugin marketplace add wei-ai-lab/clinical-trial-design
/plugin install clinical-trial-design@wei-ai-lab

After install, restart Claude Code so it loads the bundled MCP server. Confirm with /plugin (clinical-trial-design should be listed and enabled at version 0.0.13).

Method B — host shell (equivalent, scriptable)

claude plugin marketplace add wei-ai-lab/clinical-trial-design
claude plugin install clinical-trial-design@wei-ai-lab
claude plugin list      # confirm: clinical-trial-design@wei-ai-lab, version 0.0.13, enabled

If anything goes wrong, claude plugin validate /full/path/to/clinical-trial-design will tell you whether the marketplace + plugin manifests parse cleanly.

Quick local-dev alternative — skip the marketplace step and load the plugin directly from a checkout:

git clone https://github.com/wei-ai-lab/clinical-trial-design ~/clinical-trial-design
claude --plugin-dir ~/clinical-trial-design

Environment overrides

The MCP server auto-discovers Rscript in the usual locations (/opt/R/<version>/bin/, /usr/local/lib/R/bin, /usr/lib/R/bin, /usr/lib64/R/bin, /usr/local/bin, /usr/bin, /opt/homebrew/bin, /Library/Frameworks/R.framework/Resources/bin). For non-standard installs, override:

• DESIGNR_RSCRIPT=/full/path/to/Rscript — explicit path to your R binary.
• DESIGNR_LAUNCHER=/full/path/to/launcher.R — override the R launcher (rare).

Posit Workbench, RStudio Server, VS Code Remote, and other sandboxed Claude Code hosts

Claude Code in these environments doesn't always inherit your shell's environment when it spawns the MCP server. Set the env var in ~/.claude/settings.json (NOT just ~/.bashrc):

{
  "env": {
    "DESIGNR_RSCRIPT": "/opt/R/4.5.1/bin/Rscript"
  }
}

As of v0.0.14, the auto-discovery walk usually finds Posit Workbench's managed installs at /opt/R/<version>/bin/Rscript automatically, so the env override is only needed for non-standard setups. If you still see rscript_spawn_failed, the error message now reports exactly which paths were checked.

(The DESIGNR_* prefix is preserved as a wire-format contract; see API_STABILITY.md.)

Standalone MCP server (without Claude Code)

The MCP server is published to npm as clinical-trial-design. Any MCP-aware client (Claude Desktop, Cursor, Continue, custom MCP host) can launch it via npx:

npx clinical-trial-design@latest

The package bundles the R sources under r/; the launcher resolves them via import.meta.url so it works from a global install, a local install, or npx. CRAN dependencies (above) still need to be in your R user library.

Updating

Method A — slash command (inside Claude Code):

/plugin update clinical-trial-design@wei-ai-lab

Method B — host shell:

claude plugin update clinical-trial-design@wei-ai-lab

Restart Claude Code after updating.

Try it

Five conversational prompts you can paste into Claude Code once the plugin is installed. Each demonstrates a v0.0.13 capability:

1. Fixed binary superiority with reasoning chain (CAPTURE-style)

   "Design a Phase 3 trial for refractory unstable angina. Control 30-day event rate ≈ 15%, hoped-for treatment rate ≈ 9%, two-sided α = 0.05, power 80%, 1:1. Cite the precedent for the assumed effect size."

   Expect design_binary (design_class = "fixed") with N ≈ 1,000 and a populated reasoning_chain (the agent should tag the alpha as fda_guidance, the precedent-derived effect as llm_precedent).

2. Group-sequential survival under PH, regulatory-default events

   "Phase 3 oncology, single-primary OS, 1L metastatic. Median 11 vs 17 mo (HR ≈ 0.65), 2:1 randomization, 5% two-sided, 80% power, three analyses at 50%, 75%, 100% information time, OBF spending. 25 patients/month accrual, 12-month minimum follow-up, 5%/year dropout."

   Expect design_survival (model="ph", design_class="group-sequential") with events ≈ 190 (Schoenfeld + OBF inflation), boundaries (2.96, 2.36, 2.01), and a Word/PDF report on follow-up if you ask for one. Pass events_calc="lachin-foulkes" if you want the v0.0.7 default behavior; "schoenfeld" is the new default and matches regulatory convention.

3. CVOT with annualized event rate (v0.0.13's control_hazard_rate)

   "Cardiovascular outcomes trial. Control event rate is 2.5% per patient-year, target HR 0.80, 1:1, 2.5% one-sided, 90% power, fixed-sample. We'll enroll 200 patients/month and need at least 12 months of follow-up after the last enrollment."

   Expect design_survival to accept control_hazard_rate = 0.025 directly (no need to translate to a median first), use the operational block to solve duration, and report an events count in the high hundreds.

4. Co-primary PFS + OS, hierarchical (KEYNOTE-189-style)

   "Phase 3 1L NSCLC. Co-primary PFS and OS, hierarchical (PFS first, then OS). 2:1 randomization. PFS HR 0.50, control median 4.7 mo. OS HR 0.70, control median 17 mo. 80% power per endpoint, α = 0.025 one-sided. Plan a 20-month accrual, 12-month minimum follow-up for PFS / 24 months for OS. Report a Word document at the end."

   Expect design_co_primary with strategy = "fixed-sequence". OS will drive the total N. Both endpoints sized at full alpha = 0.025 (NOT alpha-split). Final tool call to design_report(format = "docx").

5. Operational kernel + feasibility warning

   "For prompt 1 above, we can enroll 80 patients/month with at least 3 months follow-up — and we can't go above 1,000 patients total."

   Expect the operational block to derive accrual_duration ≈ 12.5 months, total study duration ≈ 15.5 months, plus a feasibility_warnings entry on the result if N exceeds the 1,000 cap (it doesn't quite — should land ~960). For a violation case, ask for power 90% with the same constraints and watch the warning surface.

For an end-to-end reproducible example, see examples/:

• 01_capture_binary — binary fixed superiority
• 02_paradigm_hf_survival — TTE PH fixed
• 03_keynote024_maxcombo — TTE NPH MaxCombo
• 04_keynote189_co_primary — co-primary hierarchical
• 05_keynote042_multi_population — nested PD-L1 strata

Each is a runnable run.R plus a narrative README.md. The full 18-prompt smoke matrix is in mcp-server/SMOKE.md.

Roadmap

In priority order based on the corpus's family weights and current LLM-benchmark gaps:

1. NPH evaluation step — pharma-skills' workflow gate where a PH design is followed by an NPH-evaluation pass that reports power under both PH and NPH assumptions. Currently NPH is a model selector, not an eval step.
2. Piecewise control hazard for design_survival (currently scalar exponential only).
3. verify_design for NPH GS designs (maxcombo / wlr / ahr group-sequential).
4. Adaptive sample-size re-estimation (corpus: adaptive-ssr/) — rpact::getSampleSizeRates + Promising-Zone rule.
5. Adaptive treatment selection / population enrichment (corpus: adaptive-selection/, adaptive-enrichment/).
6. MAMS (corpus: mams/) — MAMS::mams or rpact::getDesignMams.
7. Recurrent events (corpus: recurrent-events/).
8. Count / rate endpoints (corpus: count-rate/).
9. Bayesian designs (corpus: bayesian/).
10. Platform / basket / umbrella (corpus: platform/, basket/, umbrella/).

Each row above already has ≥ 7 curated benchmark cases ready as regression anchors. See BETA_HANDOFF.md for items pending before the v0.5.0 beta tag.

Related work

RConsortium/pharma-skills is a complementary R Consortium working group skill collection focused on survival group-sequential designs with deep multi-hypothesis support and a Word-report deliverable backed by a Python template. As of v0.0.8, clinical-trial-design ships its own multi-hypothesis tools (design_co_primary, design_multi_population, design_graphical_multiplicity) covering hierarchical alpha control, biomarker subgroup + ITT patterns, and Maurer-Bretz alpha recycling.

The two projects still solve adjacent problems with different shapes: clinical-trial-design is broad and MCP-native (validated tools across the gsDesign / gsDesign2 / graphicalMCP surface, no local R session needed; cost-cheap because the agent doesn't reload skill content per turn), while pharma-skills runs in the user's local R session and requires lrsim() simulation pass before declaring a design done.

clinical-trial-design's verify_design adopts the same simulation-verification convention (±2 pp power / ±0.5 pp Type I tolerance) so a design produced here can be subjected to the same credibility floor.

Contributing

clinical-trial-design welcomes contributions from both human biostatisticians and AI agents. Two entry points:

• AGENTS.md — codebase tour and conventions written for AI-agent contributors. Covers the four-layer architecture, a concrete walkthrough of adding a new design wrapper, the benchmark anchor schema, the agent-contributor protocol, and the reasoning-chain conventions.
• CONTRIBUTING.md — human-facing process: priority list, PR checklist, review expectations.

The highest-impact contribution is a new benchmark anchor — see .github/ISSUE_TEMPLATE/add-benchmark-case.yml for the machine-fillable template that mirrors benchmarks/schema/design.schema.json.

Trust boundary and hosting

• SECURITY.md — clinical-trial-design's statelessness as a design property: the R package and MCP server are CI-gated against disk writes and network calls (.github/workflows/security-grep.yml). Any PR introducing forbidden patterns (writeLines, saveRDS, download.file, httr::, fs.writeFile, fetch, http.request, …) fails before merge. Confidential trial inputs you give the agent never leave your conversation through the plugin.
• HOSTING.md — three deployment profiles: small-co. on public Claude Code (no persistence wanted), large-enterprise on Claude Code Enterprise + Bedrock private endpoint (corporate transcript retention as audit log), and air-gapped (forthcoming). Persistence and audit are host concerns; the plugin stays the same.
• API_STABILITY.md — what's frozen (MCP tool names, result-JSON top-level shape, source_type enum, error-class names) vs flexible (tool descriptions, defaults, internal helpers).

License

Apache License 2.0. All R code, MCP server, skill content, and benchmark corpus.