MCPFax Agent Continuity

Resume the work, not the conversation — from any agent, any provider, any runtime. A checkpoint written by one model is resumable by another.

Conversation history is a hundred pages; work state is about three kilobytes. resume_packet hands a cold-starting agent a briefing — objective, last verified state, what arrived while it was gone, the next action — composed from its checkpoint plus facts we observed ourselves. Plus a mailbox to leave work for your future self or another agent, and the correctness primitives that stop an amnesiac agent paying twice.

Every tool is a plain HTTP POST; MCP is a wrapper over the same code at the same price. No account, no API key, no OAuth — an x402 wallet is the whole onboarding.

This is not a scheduler. You cannot wake a stateless session; it is gone. What happens instead is that a new invocation starts and finds its work already waiting. Nothing stays alive and nothing polls on your behalf.

Pricing. Free to write. $0.002 only when a call delivers information you did not have — and never twice for the same fact, where each record remembers its last 32 distinct billed answers. Nothing to tell you means nothing to pay.

ToolRoutePriceDoes
register/v1/registerfreeCreate (or re-derive) a namespace and its public mailbox address.
whoami/v1/whoamifreeYour agent address, registration state and how much work is waiting.
claim/v1/claim$0.002First caller wins; every later caller is told it was already done.
complete/v1/completefreeRecord the outcome so a later duplicate attempt gets the answer.
lease/v1/lease$0.002Only one holder at a time, with an expiry so a dead holder cannot deadlock.
lease_renew/v1/lease/renewfreePush out the expiry of a lease you still hold.
lease_release/v1/lease/releasefreeHand the lock back before it expires.
resume_packet/v1/resume$0.002A synthesized briefing for an agent starting cold on existing work.
checkpoint_put/v1/checkpoint/putfreeSave a structured, resumable snapshot of long work.
checkpoint_get/v1/checkpoint/get$0.002Fetch the stored checkpoint exactly as written, without synthesis.
watermark_set/v1/watermark/setfreeStore your position in a stream.
watermark_get/v1/watermark/get$0.002Fetch your last recorded position in a stream.
seen_add/v1/seen/addfreeAdd items to a durable seen-set.
seen_check/v1/seen/check$0.002Return only the items you have not seen before.
retry_state/v1/retry-state$0.002How many times this has been tried, and how long to wait.
send/v1/mail/sendfreeQueue work in another agent's mailbox (or your own).
inbox_schedule/v1/inbox/schedulefreeQueue a task envelope into your OWN mailbox, now or later.
inbox_poll/v1/inbox/poll$0.002Take the next due task envelope and claim it with a visibility timeout.
inbox_ack/v1/inbox/ackfreeAcknowledge a polled task so it is not redelivered.
inbox_nack/v1/inbox/nackfreeReturn a claimed task to the queue, optionally after a delay.
heartbeat/v1/heartbeatfreeRecord a liveness beat; if the next one is late, agreed actions run once.
budget_record/v1/budget/recordfreeAppend one amount to a scope's spend ledger.
budget_check/v1/budget/check$0.002Total, count and per-label breakdown of a scope's recorded spend.
barrier_create/v1/barrier/createfreeWake a joiner when enough agents finish — or when the deadline passes.
barrier_signal/v1/barrier/signalfreeCount one participant in; the same participant twice counts once.
barrier_status/v1/barrier/status$0.002Who has signalled, who has not, and whether the join has fired.
work_push/v1/work/pushfreeEnqueue items once, then exit. Workers pull them independently.
work_take/v1/work/take$0.002Claim up to n items exclusively, with a lease that returns them if you die.
work_done/v1/work/donefreeComplete an item you hold, optionally storing its result.
work_fail/v1/work/failfreeReturn an item for retry, or mark it permanently failed.
work_status/v1/work/status$0.002Counts, results so far, and every dead-lettered item with its reason.
job_cancel/v1/job/cancelfreeSet the stop flag workers check between items.
should_continue/v1/job/should-continue$0.002The cheap between-items check that tells a worker to stop.

Free: / /health /llms.txt /openapi.json /server.json, and MCP initialize + ping + tools/list. Paid routes take POST with a signed x402 X-PAYMENT header (USDC on Base). Start at /llms.txt.