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AtCoder MCP Server

Official registry Search and web

Search AtCoder problems and fetch public problem statements through MCP.

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http atcoder-mcp-server 'https://api.ksrnyx.top/oj-mcp/atcoder/mcp'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "atcoder-mcp-server": {
            "type": "http",
            "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. AtCoder MCP Server
  2. Quick Start
  3. What It Can Do
  4. Run Locally
  5. Availability
  6. Source and Safety
  7. Platform Rules
  8. Development
  9. License

AtCoder MCP Server

简体中文

Find and read past AtCoder problems through MCP, locally or over hosted HTTP.

Quick Start

Add the hosted server to your MCP configuration:

{
  "servers": {
    "atcoder": {
      "type": "http",
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

The endpoint accepts anonymous read requests. It does not need an API key, Cookie, or judge account.

Then ask:

Fetch AtCoder problem abc086_a and show its samples.

What It Can Do

ToolPurpose
oj_capabilitiesReport the available AtCoder read operations and transport.
oj_healthReport process readiness and the latest upstream read.
oj_fetch_problemFetch one past problem by canonical URL or contest/task id.
oj_search_problemsResolve an exact task URL or contest/task identifier.

Run Locally

Requires Node.js 22 or newer.

npm ci
npm run check
npm run build
node packages/atcoder/dist/index.js

MCP client configuration from a source checkout:

{
  "servers": {
    "atcoder": {
      "type": "stdio",
      "command": "node",
      "args": ["/absolute/path/packages/atcoder/dist/index.js"]
    }
  }
}

Tagged GitHub releases attach a standalone npm tarball.

Availability

  • Hosted MCP: https://api.ksrnyx.top/oj-mcp/atcoder/mcp
  • Official MCP Registry: io.github.ketherworks/atcoder, described by server.json
  • Health status: see the repository homepage or call oj_health

Source and Safety

This standalone release is generated from the reviewed Competitive Programming MCP source. The release package bundles the shared OJ contract implementation, so its runtime does not depend on unpublished workspace packages.

Platform Rules

Do not use this server during ongoing ABC, ARC, or AGC contests. AtCoder's current generative-AI rules generally prohibit that use. This project is intended for practice with past problems. It is unofficial and is not affiliated with or endorsed by AtCoder Inc. Problem content remains subject to the AtCoder Terms of Use.

The server exposes no run or submit tool. It accepts no judge account credentials. See SECURITY.md for the security boundary and PROVENANCE.md for the canonical source revision.

Development

npm ci
npm run check
npm run pack:check
npm run deploy:dry

License

Adapter source code is MIT licensed. Judge problem content and trademarks are not relicensed by this repository.

Frequently asked questions

What is AtCoder MCP Server?

Search AtCoder problems and fetch public problem statements through MCP.

How do I install AtCoder MCP Server?

It runs as a remote server. In Claude Code: claude mcp add --transport http atcoder-mcp-server 'https://api.ksrnyx.top/oj-mcp/atcoder/mcp'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does AtCoder MCP Server need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is AtCoder MCP Server open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains AtCoder MCP Server?

It is published by ketherworks. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.