# A/B Test Sample Size Calculator MCP (remote · ab-test-sample-size-calculator-mcp.lipmichal.workers.dev)

Exact A/B test sample size, duration, z-test, chi-square, Fisher-Freeman-Halton and peeking risk.

- Trust score: 64/100 (medium)
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `ab-test-sample-size-calculator-mcp.lipmichal.workers.dev`: 64/100 (this document), [markdown](https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp.md), [page](https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp)

## Channel facts

- Endpoint: `https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.0`

## 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 2026-11-05.

- **Endpoint Security**: 63/100
  - 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 enforcement could not be verified: the plaintext port answered with HTTP 405, which proves neither a plaintext path nor enforcement.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - 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**: 57/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1091 tokens (~218/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**: 10/100
  - Stability observed for 3 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 93/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 79% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - 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 A/B Test Sample Size Calculator MCP server?

A/B Test Sample Size Calculator MCP is a hosted endpoint at https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/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 theluckystrike-ab-test-sample-size-calculator-mc 'https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "theluckystrike-ab-test-sample-size-calculator-mc": {
      "url": "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "theluckystrike-ab-test-sample-size-calculator-mc": {
      "type": "http",
      "url": "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.theluckystrike-ab-test-sample-size-calculator-mc]
url = "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "theluckystrike-ab-test-sample-size-calculator-mc": {
      "type": "remote",
      "url": "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add theluckystrike-ab-test-sample-size-calculator-mc --url 'https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  theluckystrike-ab-test-sample-size-calculator-mc:
    url: "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "theluckystrike-ab-test-sample-size-calculator-mc": {
      "Transport": "http",
      "Url": "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add theluckystrike-ab-test-sample-size-calculator-mc -t streamable-http -u 'https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp'
```

### Other

```json
{
  "mcpServers": {
    "theluckystrike-ab-test-sample-size-calculator-mc": {
      "type": "http",
      "url": "https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/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.

### 2026-11-04 (score 64, +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.

### 2026-11-03 (score 63, 0)

- [functional improvement] Stability: unverified → 0.03

### 2026-11-02 (score 63)

First indexed and scored.

## MCP tools (5)

### `calculate_sample_size` (~302 tokens)

A/B test sample size calculator

Exact sample size per variant for an A/B test on a conversion rate (two independent proportions): baseline rate, minimum detectable effect (relative or absolute), alpha, power, one or two-sided, several variants with optional Bonferroni, and unequal allocation. Uses the pooled/unpooled normal formula (same as R power.prop.test) and also reports the figure Evan Miller's calculator gives, so the two can be reconciled.

Input parameters:

- `allocation_ratio` (number): Users in each variant per user in control. 1 = even split.
- `alpha` (number): Significance level, default 0.05.
- `baseline_rate` (number, required): Control conversion rate as a proportion, for example 0.042 for 4.2%.
- `bonferroni` (boolean): Split alpha across the variant-vs-control comparisons (Bonferroni).
- `mde` (number, required): Minimum detectable effect. Relative by default (0.10 = a 10% lift); set mde_type "absolute" for percentage points as a proportion (0.01 = 1 point).
- `mde_type` (string): relative (default) or absolute.
- `power` (number): Statistical power, default 0.80.
- `sided` (string): two-sided (default) or one-sided test.
- `variants` (integer): Number of arms including control. 2 = A/B, 3 = A/B/C.

### `estimate_test_duration` (~207 tokens)

A/B test duration estimator

How many days an A/B test must run: from a known sample size per variant, or from baseline rate and MDE (computed as in calculate_sample_size), plus daily visitors and the share of traffic in the test. Returns exact days and the recommended whole weeks (to cover weekday effects).

Input parameters:

- `alpha` (number): Significance level, default 0.05.
- `baseline_rate` (number): Control conversion rate, for computing the sample size.
- `daily_visitors` (number, required): Eligible visitors per day across the whole site or page.
- `mde` (number): Minimum detectable effect (relative by default).
- `mde_type` (string)
- `power` (number)
- `sample_size_per_variant` (integer): Known users per arm. If omitted, give baseline_rate and mde.
- `traffic_share` (number): Fraction of those visitors entered into the test, default 1.
- `variants` (integer): Number of arms including control.

### `test_ab_significance` (~185 tokens)

A/B test significance calculator

Is an A/B test result statistically significant? From visitors and conversions per group: two-proportion z-test (pooled), one or two-sided p-value, Wald confidence interval for the difference, relative lift, Pearson chi-square with and without Yates correction (R prop.test), Fisher exact p for the same 2x2 table, and a sample ratio mismatch (SRM) check against the planned split.

Input parameters:

- `alpha` (number): Significance level, default 0.05.
- `alternative` (string): greater = variant converts better than control.
- `control_conversions` (integer, required)
- `control_visitors` (integer, required)
- `expected_split` (number): Planned share of traffic in control, for the SRM check. Default 0.5.
- `variant_conversions` (integer, required)
- `variant_visitors` (integer, required)

### `fisher_exact_test` (~164 tokens)

Fisher exact and Fisher-Freeman-Halton test

Exact p-value for a contingency table of counts. 2x2: Fisher exact test (two-sided, greater or less, as R fisher.test). Larger r x c tables (for example 3 variants x converted/not, or 4 x 4 survey tables): Fisher-Freeman-Halton exact test by a network algorithm. Also returns Pearson chi-square and how many cells have expected counts below 5, so you can see when the chi-square approximation is unsafe.

Input parameters:

- `alternative` (string): One-sided options apply to 2x2 only; greater = odds ratio above 1.
- `table` (array, required): Rows of counts, for example [[12, 488], [25, 475]] (rows = groups, columns = outcomes).

### `check_peeking_risk` (~139 tokens)

A/B test peeking and sequential testing risk

What peeking does to an A/B test: the real false positive rate if you check a fixed-horizon test K times and stop at the first p < alpha (for example about 14% at 5 looks with alpha 0.05), and the Pocock and O'Brien-Fleming group sequential boundaries (z and nominal p per look) that keep the overall rate at alpha, for up to 10 equally spaced looks.

Input parameters:

- `alpha` (number): Significance level, default 0.05.
- `looks` (integer, required): How many times the result is checked, including the final look. Equally spaced.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp#diagnostics

## Score history

- 2026-11-05: 64
- 2026-11-04: 64
- 2026-11-03: 63
- 2026-11-02: 63

## Common questions

### What is the A/B Test Sample Size Calculator MCP server?

A/B Test Sample Size Calculator MCP is listed in the public MCP registry as io.github.theluckystrike/ab-test-sample-size-calculator-mcp. Exact A/B test sample size, duration, z-test, chi-square, Fisher-Freeman-Halton and peeking risk. This page covers its hosted endpoint (https://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp).

### Is the A/B Test Sample Size Calculator MCP server safe to use?

A/B Test Sample Size Calculator MCP scores 64 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 A/B Test Sample Size Calculator MCP server expose?

A/B Test Sample Size Calculator MCP exposes 5 tools: calculate_sample_size, estimate_test_duration, test_ab_significance, fisher_exact_test, check_peeking_risk. Their descriptions and schemas cost roughly 997 tokens of context every time the server is loaded.

### Does the A/B Test Sample Size Calculator MCP server require authentication?

No. We connected to A/B Test Sample Size Calculator MCP without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the A/B Test Sample Size Calculator MCP server still maintained?

A/B Test Sample Size Calculator MCP is still listed as active in the MCP registry. We last reached this channel on 5 November 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://ab-test-sample-size-calculator-mcp.lipmichal.workers.dev/mcp
- Repository: https://github.com/theluckystrike/ab-test-sample-size-calculator-mcp
- Website: https://abwex.com/tools/sample-size-calculator.html
- Changelog RSS feed: https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp.json
- HTML version of this page: https://verifymcp.io/servers/theluckystrike-ab-test-sample-size-calculator-mcp/ab-test-sample-size-calculator-mcp