AtCoder MCP Server

by ketherworks Your server? Claim it

answering

AtCoder MCP Server is answering right now. Last checked 9 min ago. It exposes 4 tools. Last commit 8 Sep 2026.

Search AtCoder problems and fetch public problem statements through MCP.

Uptime history 47 days of history · worst day 97%

47 days agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

570 ms

Response time

average over 24h

Stars

last commit 8 Sep 2026

Nothing serious here today

Today is the operative word: we check AtCoder MCP Server every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 9 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add atcoder --transport http https://api.ksrnyx.top/oj-mcp/atcoder/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "atcoder": {
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

~/.codex/config.toml

[mcp_servers.atcoder]
url = "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "atcoder": {
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

.vscode/mcp.json

{
  "mcpServers": {
    "atcoder": {
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

Available tools 4

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

capabilities

oj_capabilities

Report the audited anonymous AtCoder read surface and explicitly unsupported operations.

health

oj_health

Report local readiness and the latest observed AtCoder page-read status without probing upstream.

problem

oj_fetch_problem

Fetch one public problem statement from an exact contest/task pair or canonical atcoder.jp task URL. Returns sanitized HTML with preserved math, samples, limits, hashes, and source provenance.

problems

oj_search_problems

Resolve exactly one contest/task id, atcoder:contest/task id, or canonical task URL. Free-text and catalog crawling are not supported.

Endpoints

URL	Transport	State	Latency	Checked
https://api.ksrnyx.top/oj-mcp/atcoder/mcp	streamable-http	answering	538 ms	9 min ago

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AtCoder MCP Server — questions

Answers built from our own checks of this server.

What can AtCoder MCP Server do?

It exposes 4 tools, read directly from the server on our last check. Among them: oj_capabilities, oj_fetch_problem, oj_health, oj_search_problems. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is AtCoder MCP Server working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 570 ms. The bar chart above shows every period we have measured.

How do I connect AtCoder MCP Server?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does AtCoder MCP Server need an API key?

No. AtCoder MCP Server completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 4 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is AtCoder MCP Server?

It answers our handshake in 570 ms on average, which is faster than 23% of all working MCP servers we measure. That is on the slow side — worth knowing if the tool sits inside an interactive loop. The comparison comes from our own checks across the whole registry, every 15 minutes.

Is AtCoder MCP Server open source?

Yes — it is published under the MIT licence, written in TypeScript and 0 stars on GitHub. The source link is on this page, so you can read exactly what it does with your data before you connect it.