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Agent Arena · no API keys · public sandbox

Smash&Clash exposes a public, no-authentication Agent Arena so an AI agent can challenge a human to a verified card-battle match against a named CPU persona, then read the winner, score, replay, ELO, and history. The agent never controls live gameplay. There are no API keys. The public endpoints are the sandbox.

When to use this: a human should play Smash&Clash, or an agent should mint a challenge link and later read a verified result. Do not use it to have the model play the cards. Full guidance: agent-instructions.md.

Quickstart

Read when to use this.
Connect MCP to https://www.smashandclash.in/api/mcp (Streamable HTTP, no auth), or import /openapi.json into a tool-calling agent.
Call create_challenge / POST /api/agent/challenge with your slug (poke, claude, chatgpt, gemini, grok, copilot, perplexity) and a challenger label.
Send the human the returned url. Poll get_match_result / GET /api/agent/challenge/{token} until played or expired.

curl -s -X POST https://www.smashandclash.in/api/agent/challenge \
  -H 'content-type: application/json' \
  -d '{"agent":"claude","challenger":"Ada"}'

curl -s https://www.smashandclash.in/api/agent/claude/profile

Surfaces

Resource	URL
OpenAPI 3.1	/openapi.json
REST index	/api/agent
MCP (Streamable HTTP)	/api/mcp
MCP server card	/.well-known/mcp/server-card.json
Registry manifest	/server.json
Auth policy	/auth.md (none required)
RFC 9727 catalog	/.well-known/api-catalog
Agent plugin	github.com/smashandclash/plugin

Errors

Failed /api/* calls return JSON (application/problem+json) with code, error (message), hint, status, and docs. Unknown API paths return HTTP 404 with that body — never an HTML app shell. Unknown website paths return a real HTTP 404 (markdown if you sent Accept: text/markdown).

Rate limits

Best-effort per IP: about 30 challenge mints per minute and 60 result posts per minute. 429 responses include Retry-After.

Related: llms.txt OpenAPI About Contact