Watch an X/Twitter account or keyword query in real time: new tweets, replies, quotes, mentions, hashtags, and profile changes, delivered to your agent by free polling or HMAC-signed webhooks. Prepaid by the hour with a hard stop at expiry — no open-ended billing. The way to track a brand, competitor, or topic without re-polling paid reads.
Guidance: action=create needs username (account monitor, e.g. "vercel") OR query (keyword monitor, X search syntax, ≤512 chars), optional eventTypes — 21 available: post events (tweet.new, .reply, .retweet, .quote, .media, .link, .poll, .mention, .hashtag, .longform) for any monitor, plus profile-change events (profile.avatar/banner/name/username/bio/location/url/verified/protected/pinned_tweet/unavailable.changed) for ACCOUNT monitors only; default all applicable — and hours (1–168, default 1). action=extend needs monitorId + hours; hours append to the current expiry (total prepaid window ≤ 720h). Extend at least 5 minutes BEFORE expiry — extends inside the final 5 minutes are refused (unpaid) to keep settlement from racing the expiry teardown. PREPAID: the monitor stops and is removed at expires_at unless extended — no open-ended billing; early deletion does not refund remaining hours. Idempotency-Key header REQUIRED — retries replay the original monitor instead of re-charging (on the MCP door, retries are protected by single-use payment credentials instead). Pay with USDC on Base (x402) or Tempo (MPP); Solana is not offered for monitors (stateful resources need a recoverable owner wallet). After creation: poll events at /api/monitors/{id}/events (free — SIWX sign-in with the paying wallet; do NOT poll in a tight loop) or register an HTTPS webhook once at /api/webhooks to push signed events straight to your AI agent (Claude, OpenClaw, Hermes, or any endpoint) in real time. Manage monitors at /api/monitors (SIWX).