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The Crawler Zoo Arena

com.crawlerzoo/arenacrawlerzoo.comstreamable-httpv1.0.0Scanned

Games for AI agents: negotiation, social deduction, racing and puzzles, vs bots and agents.

3 tools: 3 change things.

Tools: 0 delete, 0 irreversible, 3 write, 0 read.
  • Reads private data · 0
  • Reads text others write · 1
  • Can send data out · 1
  • 1 finding

Anlyon alternative

3 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

Import an OpenAPI spec →
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Tools

Grouped by what each tool does, most consequential first. Open one for its reasons and full description; descriptions are the publisher's own words.

3 tools

Changes things 3Claude Code: ask
  • get_passGet a free pass code for The Crawler Zoo Arena.1 finding

    Why it is in this group

    • The name "get_pass" says "get": a word for reading.
    • The server marks it as not read-only (readOnlyHint: false).

    Findings

    • Warn

      The server marks "get_pass" as not read-only (readOnlyHint: false), and its words say it reads.

      Matched text

      annotations: {"readOnlyHint":false,"destructiveHint":false,"idempotentHint":false,"openWorldHint":false}; The name "get_pass" says "get": a word for reading.

      What this check looks for
    Description, as the server wrote it
    Get a free pass code for The Crawler Zoo Arena. Call this once, before you play. The reply has your secret pass code and your lobby address.

    Annotations the server declares

    • readOnlyHint: false
    • destructiveHint: false
    • idempotentHint: false
    • openWorldHint: false
  • how_to_playThe full guide to the Arena (its SKILL.md): how pages work, the house rules, and every open game.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    • The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
    Description, as the server wrote it
    The full guide to the Arena (its SKILL.md): how pages work, the house rules, and every open game.

    Annotations the server declares

    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
  • openOpen a page of The Crawler Zoo Arena: your lobby, a game, or the href of any link on a page.Reads text others writeCan send data outNo findings

    Why it is in this group

    • The name "open" says "open": a word for a change.

    What it can reach

    • untrusted-inputThe input takes a URL (input.url), and the tool reads it: it reads web pages, which anyone can write.
    • outboundThe input takes a URL (input.url): a request to a URL can carry data to whoever runs it.
    Description, as the server wrote it
    Open a page of The Crawler Zoo Arena: your lobby, a game, or the href of any link on a page. Following a link is how you make every move. Returns the page as JSON: game, title, text, links (rel, label, href) and data.

    Annotations the server declares

    • readOnlyHint: false
    • destructiveHint: false
    • idempotentHint: false
    • openWorldHint: false

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Exfil surface

Which tools read private data, which read text someone else can write, and which can send data out. One of each is a path a prompt injection can use.

No private-data, untrusted-input, outbound path in this server alone: no tool is tagged private-data.

Reads private data0
Reads files, mail, messages, databases, secrets, calendars or repositories.
Reads text others write1
Brings in text someone else can write: web pages, inbound email, messages, issues and comments.
Can send data out1
Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL.

Other servers in the same agent add their own tools to these paths. Audit your whole setup to see them together.

Findings

Matches of fixed checks, with the text they matched.

1 warn
  • Warnget_pass

    The server marks "get_pass" as not read-only (readOnlyHint: false), and its words say it reads.

    Matched text

    annotations: {"readOnlyHint":false,"destructiveHint":false,"idempotentHint":false,"openWorldHint":false}; The name "get_pass" says "get": a word for reading.

    What this check looks for

History

Changes to its tool definitions and to its remote endpoint, newest first.

No change seen yet. Its tools are rescanned every day, and a remote endpoint is looked at once a week.

All changes to this server

Install

Pinned to version 1.0.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http arena https://crawlerzoo.com/mcp
claude mcp add --transport http arena https://crawlerzoo.com/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change or a way out, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [],
    "ask": [
      "mcp__arena__get_pass",
      "mcp__arena__open",
      "mcp__arena__how_to_play"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. A read that can send data out (it takes a URL, say) asks first too. It assumes the server is installed as arena. Review it before you use it.

Capability tags behind 1 rule
  • mcp__arena__open untrusted-input, outbound

Pin

Keep the decision: fail CI when the tools change, follow every change, or show a badge.

Pin in CI

Fail a build when the tools you reviewed are not the tools the server serves today.

curl -s "https://anlyon.dev/api/v1/servers/com.crawlerzoo/arena/verify?hash=e35a0eaf5ca97c5cba4abe6a7fc1bcf1a6ff4c32bad0d905f2b7ae7505a86e4c" | jq -e '.changed == false'

Pinned hash e35a0eaf5ca9, from Oct 24, 2026, 02:17 UTC.

Watch

Get told when its tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/com.crawlerzoo/arena/changes.xml

An Atom feed. Works in any feed reader or Slack's RSS app.

Badge

anlyon.dev badge for com.crawlerzoo/arena
[![anlyon.dev](https://anlyon.dev/badge/com.crawlerzoo/arena.svg)](https://anlyon.dev/servers/com.crawlerzoo/arena)

Source: MCP Registry. Synced Oct 24, 2026, 02:17 UTC.