# OpenCancer (remote · opencancer.ai)

Cancer patient expert: NCCN-grounded answers with sources, recruiting trials, and expert review.

- Trust score: 77/100 (medium)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-10-25

## Components

- remote · `opencancer.ai`: 77/100 (this document), [markdown](https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp.md), [page](https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp)

## Channel facts

- Endpoint: `https://opencancer.ai/api/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `2.0.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-10-25.

- **Endpoint Security**: 80/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 67/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 924 tokens (~184/item across 5 items; 5 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 33/100
  - Stability observed for 10 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 98/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 93% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - All 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.
  - An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the OpenCancer MCP server?

OpenCancer is a hosted endpoint at https://opencancer.ai/api/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http ai-opencancer-opencancer 'https://opencancer.ai/api/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "ai-opencancer-opencancer": {
      "url": "https://opencancer.ai/api/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "ai-opencancer-opencancer": {
      "type": "http",
      "url": "https://opencancer.ai/api/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.ai-opencancer-opencancer]
url = "https://opencancer.ai/api/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "ai-opencancer-opencancer": {
      "type": "remote",
      "url": "https://opencancer.ai/api/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add ai-opencancer-opencancer --url 'https://opencancer.ai/api/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  ai-opencancer-opencancer:
    url: "https://opencancer.ai/api/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "ai-opencancer-opencancer": {
      "Transport": "http",
      "Url": "https://opencancer.ai/api/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add ai-opencancer-opencancer -t streamable-http -u 'https://opencancer.ai/api/mcp'
```

### Other

```json
{
  "mcpServers": {
    "ai-opencancer-opencancer": {
      "type": "http",
      "url": "https://opencancer.ai/api/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-10-25 (score 77, +1)

No change was recorded against any check on this day. Stability & Change Management went from 30 to 33. That category is still filling its 30-day observation window: 9 days of observed history at the previous scan, 10 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-23 (score 76, +1)

No change was recorded against any check on this day. Stability & Change Management went from 23 to 27. That category is still filling its 30-day observation window: 7 days of observed history at the previous scan, 8 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-21 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 17 to 20. That category is still filling its 30-day observation window: 5 days of observed history at the previous scan, 6 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-19 (score 74, +1)

No change was recorded against any check on this day. Stability & Change Management went from 10 to 13. That category is still filling its 30-day observation window: 3 days of observed history at the previous scan, 4 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-17 (score 73, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-16 (score 72, 0)

- [security] The server rewrote its instructions, which are the text every model session reads
- [security] Tool “ask_opencancer” rewrote its description, which is the text the model reads
- [security] Tool “find_clinical_trials” rewrote its description, which is the text the model reads
- [security] Tool “get_trial_details” rewrote its description, which is the text the model reads
- [security] Tool “open_case” rewrote its description, which is the text the model reads
- [functional improvement] Schema quality: 241 → 184
- [functional improvement] Stability: unverified → 0.03
- [cosmetic] “find_clinical_trials” reworded the description of “location”
- [cosmetic] “send_feedback” reworded the description of “answer_id”

### 2026-10-15 (score 72)

First indexed and scored.

## MCP tools (5)

### `ask_opencancer` (~220 tokens)

Ask OpenCancer

Answers a cancer patient or caregiver question in plain language, grounded in NCCN Guidelines for Patients and medical literature. Covers what a diagnosis, stage, biomarker or test result means; treatment options; side effects and their management; questions for the oncologist; second opinions; living with cancer. Answers in the language of the question. Returns the answer, its sources, a disclaimer, a link to OpenCancer's care team, and an answer id. Emergencies, prognosis or life-expectancy questions, and questions about children return a safety message that routes to the care team instead of an answer. Educational information, not medical advice. Accepts no personal identifiers

Input parameters:

- `cancer_type` (string): Optional cancer type, to focus the guidelines used, e.g. "colon cancer".
- `context` (string): Optional general context such as stage or treatments tried, e.g. "stage 3, finished FOLFOX". No identifiers.
- `question` (string, required): The question in plain language, in the user's language, without personal identifiers.

Output parameters:

- `answer` (string)
- `answer_id` (string|null)
- `care_team_url` (string)
- `disclaimer` (string)
- `grounding` (object)
- `needs_human_review` (boolean)
- `review_status` (string)
- `sources` (array)

### `find_clinical_trials` (~212 tokens)

Find recruiting clinical trials

Lists clinical trials recruiting now for a cancer type, from ClinicalTrials.gov, optionally near a city, state or country and filtered by a biomarker, drug or treatment keyword and by phase. Returns up to 8 trials with NCT number, phase, sponsor, the sites closest to the requested place, a registry link, a link to the full search, and a link to an OpenCancer expert who can build a trial shortlist for a specific case. Listing a trial is not an eligibility decision; only the trial team can confirm eligibility

Input parameters:

- `condition` (string, required): Cancer type or condition, e.g. "pancreatic cancer".
- `keyword` (string): Optional biomarker, drug, or treatment, e.g. "KRAS G12C" or "CAR-T".
- `location` (string): Optional city, state, or country, e.g. "Boston" or "Germany" (city level, not a street address).
- `phase` (string): Optional trial phase.

Output parameters:

- `expert_help_url` (string)
- `search_url` (string)
- `total` (number)
- `trials` (array)

### `get_trial_details` (~93 tokens)

Get clinical trial details

Returns one clinical trial from ClinicalTrials.gov by its NCT number: what it tests, phase, status, last registry update, ages, the inclusion and exclusion criteria in their original wording, recruiting sites with their status, study contacts, and the registry link. Eligibility is confirmed only by the study team

Input parameters:

- `nct_id` (string, required): ClinicalTrials.gov ID, e.g. "NCT05902169".

Output parameters:

- `ages` (string)
- `conditions` (array)
- `contacts` (array)
- `exclusion_criteria` (string)
- `expert_help_url` (string)
- `inclusion_criteria` (string)
- `interventions` (array)
- `last_updated` (string)
- `nct_id` (string)
- `official_title` (string)
- `phase` (string)
- `sex` (string)
- `site_count` (number)
- `sites` (array)
- `sponsor` (string)
- `status` (string)
- `summary` (string)
- `title` (string)
- `url` (string)

### `open_case` (~131 tokens)

Get the expert review link

Returns a link where a patient can start an expert review of their case by OpenCancer and Cancer Commons scientists (records, options, trial shortlist, next step). The link only opens an intake page: no case is created and no records are sent. The patient enters their own details and personally confirms consent on that page. Accepts no names, contact details or records.

Input parameters:

- `cancer_type` (string): Optional cancer type, e.g. "prostate cancer".
- `preferred_destinations` (array)
- `question` (string): Optional: what the patient wants experts to look at, without personal identifiers.

Output parameters:

- `available_intake_destinations` (array)
- `case_created` (boolean)
- `consent_required` (boolean)
- `intake_url` (string)
- `message` (string)
- `preferred_destinations` (array)

### `send_feedback` (~193 tokens)

Flag an answer or send feedback

Flags an OpenCancer answer for human expert review, or sends feedback to the OpenCancer team. Used when the user says an OpenCancer answer was wrong, unsafe, or incomplete, or wants to tell OpenCancer something (answer_id identifies the answer; message holds the user's words). Also used to report that an OpenCancer tool returned no usable answer (kind "missing_answer" with answer_id or tool, no message). Feedback is read by the OpenCancer team; it is not an urgent-care channel and no reply is sent through it.

Input parameters:

- `answer_id` (string): Optional. The answer id from an OpenCancer answer.
- `kind` (string, required): wrong_or_unsafe, missing_answer, bug, idea, or praise.
- `message` (string): Optional. The user's feedback in their own words. Contact details are not accepted.
- `tool` (string): Optional. Which OpenCancer tool this is about.

Output parameters:

- `duplicate` (boolean)
- `in_review_queue` (boolean)
- `saved` (boolean)

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp#diagnostics

## Score history

- 2026-10-25: 77
- 2026-10-24: 76
- 2026-10-23: 76
- 2026-10-22: 75
- 2026-10-21: 75
- 2026-10-20: 74
- 2026-10-19: 74
- 2026-10-18: 73
- 2026-10-17: 73
- 2026-10-16: 72
- 2026-10-15: 72

## Common questions

### What is the OpenCancer MCP server?

OpenCancer is an MCP server listed in the public MCP registry as ai.opencancer/opencancer. Cancer patient expert: NCCN-grounded answers with sources, recruiting trials, and expert review. This page covers its hosted endpoint (https://opencancer.ai/api/mcp).

### Is the OpenCancer MCP server safe to use?

OpenCancer scores 77 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the OpenCancer MCP server expose?

OpenCancer exposes 5 tools: ask_opencancer, find_clinical_trials, get_trial_details, open_case, send_feedback. Their descriptions and schemas cost roughly 849 tokens of context every time the server is loaded.

### Does the OpenCancer MCP server require authentication?

No. We connected to OpenCancer without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the OpenCancer MCP server still maintained?

OpenCancer is still listed as active in the MCP registry. We last reached this channel on 25 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://opencancer.ai/api/mcp
- Website: https://opencancer.ai/connectors
- Changelog RSS feed: https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp.json
- HTML version of this page: https://verifymcp.io/servers/ai-opencancer-opencancer/api-mcp