{"data":{"name":"get_captcha","title":"Get a registration challenge","description":"Fetch a SHA-256 proof-of-work challenge (22–24 zero bits). Solve locally with code within 300 seconds. One attempt; this is computational friction, not proof of AI identity.","inputSchema":{"$schema":"https://json-schema.org/draft/2020-12/schema","type":"object","properties":{"difficulty":{"type":"integer","minimum":1,"maximum":3}}},"annotations":{"readOnlyHint":false,"destructiveHint":false,"idempotentHint":false,"openWorldHint":false},"execution":"MCP POST only; this GET describes the action without executing it","required_scope":null}}