# K2 Study Decks & Algorithm (remote · k2kanji.com)

Study decks for 8 languages plus the K2 spaced-repetition engine, runnable on your items.

- Trust score: 79/100 (medium)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `k2kanji.com`: 79/100 (this document), [markdown](https://verifymcp.io/servers/com-k2kanji-study/api-mcp.md), [page](https://verifymcp.io/servers/com-k2kanji-study/api-mcp)

## Channel facts

- Endpoint: `https://k2kanji.com/api/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.1.0`

## 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**: 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**: 82/100
  - 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1330 tokens (~133/item across 10 items; 7 tools + 3 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 43/100
  - Stability observed for 13 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% 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 7 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 9 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 60/100
  - Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28.

## Install

### How do I install the K2 Study Decks & Algorithm MCP server?

K2 Study Decks & Algorithm is a hosted endpoint at https://k2kanji.com/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 com-k2kanji-study 'https://k2kanji.com/api/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "com-k2kanji-study": {
      "url": "https://k2kanji.com/api/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "com-k2kanji-study": {
      "type": "http",
      "url": "https://k2kanji.com/api/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.com-k2kanji-study]
url = "https://k2kanji.com/api/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "com-k2kanji-study": {
      "type": "remote",
      "url": "https://k2kanji.com/api/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add com-k2kanji-study --url 'https://k2kanji.com/api/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  com-k2kanji-study:
    url: "https://k2kanji.com/api/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "com-k2kanji-study": {
      "Transport": "http",
      "Url": "https://k2kanji.com/api/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add com-k2kanji-study -t streamable-http -u 'https://k2kanji.com/api/mcp'
```

### Other

```json
{
  "mcpServers": {
    "com-k2kanji-study": {
      "type": "http",
      "url": "https://k2kanji.com/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.

### 2026-11-04 (score 79, +1)

No change was recorded against any check on this day. Stability & Change Management went from 37 to 40. That category is still filling its 30-day observation window: 11 days of observed history at the previous scan, 12 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-02 (score 78, +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.

### 2026-10-31 (score 77, +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.

### 2026-10-28 (score 76, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-27 (score 75, 0)

- [security] Tool “get_cube_algorithms” rewrote its description, which is the text the model reads

### 2026-10-26 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-24 (score 74, +1)

- [functional improvement] Stability: unverified → 0.03

### 2026-10-23 (score 73)

First indexed and scored.

## MCP tools (7)

### `list_decks` (~79 tokens)

The catalog of K2 study decks: eight curated datasets spanning Japanese kanji and vocabulary, HSK Chinese, Korean Hangul, Spanish, French, classical Latin and medical Latin. Returns each deck id (the value other tools take), what it teaches, how many entries it has, and what its fields mean. Call this before search_deck.

### `search_deck` (~198 tokens)

Search one deck. `query` substring-matches the term, its reading/pronunciation, its English meanings, and its category, so "bone" finds entries glossed as bone and "ㄱ" finds that jamo. Narrow with `category` (exact, from list_decks) or `difficulty` (1-5; for the kanji deck this is the school grade). Paginated via `offset`.

Input parameters:

- `category` (string): Exact category filter (see list_decks)
- `deck` (string, required): Deck id from list_decks
- `difficulty` (number): Exact difficulty/grade filter (1-5; kanji deck = grade 1-6)
- `limit` (number): Max results (default 20, max 50)
- `offset` (number): Skip this many matches (paging)
- `query` (string): Substring to match against term, reading, meanings, category

### `get_entry` (~106 tokens)

One deck entry in full, matched on the exact term (the kanji, hanzi, jamo, or word itself). Case-insensitive. Returns every field the deck carries, including the deck-specific extras: stroke counts and JLPT level for kanji, component kanji for compounds, declension and English derivatives for Latin, IPA and pronunciation audio for French.

Input parameters:

- `deck` (string, required): Deck id from list_decks
- `term` (string, required): Exact term to fetch

### `get_cube_algorithms` (~233 tokens)

Rubik's cube last-layer algorithm sets used by the K2 cube trainer: full OLL (57 cases), full PLL (21), the two-look beginner subsets, full ZBLL, and Roux CMLL (42 cases plus a two-look subset; CMLL algorithms only need to solve the corners and keep both 1x2x3 blocks). Each case returns its primary algorithm plus alternates, with sources and finger-trick notes where recorded. Every algorithm in these sets is verified against a cube simulator by the repo's audit script (app/cube/scripts/audit-algorithms.mjs), run before data changes land. Filter by `case_id` or `group`; omit both for the set's structure and levels.

Input parameters:

- `case_id` (string): Single case id, e.g. 'oll-21' or 'pll-t'
- `group` (string): Case group filter, e.g. 'T Shapes', 'OCLL'
- `limit` (number): Max cases (default 20, max 50)
- `set` (string, required): Algorithm set id

### `explain_k2_algorithm` (~112 tokens)

The K2 spaced-repetition engine, described. K2 stores no review dates: each item holds a probability p that halves on a correct answer and doubles on a wrong one, and items are drawn by Monte Carlo rejection sampling, so the pool self-organizes around current weaknesses and expands when it cools. Returns the update rule (including the deliberate hinted-answer exception), the selection and pool-expansion mechanics, the live tuning constants, and notes for porting it. Read this before simulate_k2_session.

### `simulate_k2_session` (~210 tokens)

Run the real K2 engine over your own items. Give it a list of terms (any strings — your flashcards, cube cases, anything), a study mode, and a sequence of answers, and it returns the p-value trajectory per answer, which items are now mastered, when the pool expanded, and the probability distribution over what K2 would serve next. Use this to drive your own drilling with K2 as the scheduler instead of reimplementing it.

Input parameters:

- `mode` (string): Which dimension is being drilled (each carries its own p).
- `starting_level` (number): Treat the first N terms as already known (pre-cooled), as the app's head-start option does. Default 0.
- `steps` (array, required): Answers in order. `outcome` is correct | incorrect | hinted (hinted = answered with the crutch visible; cools more weakly).
- `terms` (array, required): The item pool. Any strings; the engine only needs identity.

### `get_site_info` (~66 tokens)

What K2 is, which apps it runs, what this server does and does not expose, and every machine-readable surface. Also returns the full capability map — every tool, prompt, and resource — so a client with a stale or tools-only roster can still see the whole surface.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-k2kanji-study/api-mcp#diagnostics

## Score history

- 2026-11-05: 79
- 2026-11-04: 79
- 2026-11-03: 78
- 2026-11-02: 78
- 2026-11-01: 77
- 2026-10-31: 77
- 2026-10-30: 76
- 2026-10-29: 76
- 2026-10-28: 76
- 2026-10-27: 75
- 2026-10-26: 75
- 2026-10-25: 74
- 2026-10-24: 74
- 2026-10-23: 73

## Common questions

### What is the K2 Study Decks & Algorithm MCP server?

K2 Study Decks & Algorithm is an MCP server listed in the public MCP registry as com.k2kanji/study. Study decks for 8 languages plus the K2 spaced-repetition engine, runnable on your items. This page covers its hosted endpoint (https://k2kanji.com/api/mcp).

### Is the K2 Study Decks & Algorithm MCP server safe to use?

K2 Study Decks & Algorithm scores 79 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 K2 Study Decks & Algorithm MCP server expose?

K2 Study Decks & Algorithm exposes 7 tools: list_decks, search_deck, get_entry, get_cube_algorithms, explain_k2_algorithm, and 2 more. Their descriptions and schemas cost roughly 1,004 tokens of context every time the server is loaded.

### Does the K2 Study Decks & Algorithm MCP server require authentication?

No. We connected to K2 Study Decks & Algorithm without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the K2 Study Decks & Algorithm MCP server still maintained?

K2 Study Decks & Algorithm 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://k2kanji.com/api/mcp
- Website: https://k2kanji.com/
- Changelog RSS feed: https://verifymcp.io/servers/com-k2kanji-study/api-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-k2kanji-study/api-mcp.json
- HTML version of this page: https://verifymcp.io/servers/com-k2kanji-study/api-mcp