preview_back

Returns the seat the key owner would take in an opinion’s backing relay, what that seat costs, and the conditional payback — plus the confirm_token back_opinion needs. Scope: write · Annotations: readOnlyHint REST equivalent: POST /open/v1/opinions/{id}/back-preview

Backing spends coins to endorse someone else’s opinion. This tool charges nothing and counts against the read window only.

Parameters

Name	Type	Required	Default	Notes
`topic_id`	string (uuid)	✅	—	The topic the opinion belongs to
`opinion_id`	string (uuid)	✅	—	From `list_topic_opinions`
`language`	see languages		`en`

Returns

my_seq_if_now is the seat the owner would take; the price rises along the relay, so the quoted price_coins belongs to that seat only. Captured live:

{
  "can_back": true,
  "summary": {
    "topic_title": "Will the Fed cut rates at the November 2026 meeting?",
    "opinion_excerpt": "Disagree. Two governors have signalled they want another quarter of data before moving, and November is early.",
    "author": {
      "id": "33333333-3333-4333-8333-333333333333",
      "handle": "kenji",
      "nickname": "Kenji Sato",
      "avatar_url": "https://cdn.seesaw.fun/avatars/20260901/kenji.png",
      "account_type": "user",
      "url": "https://seesaw.fun/profile/33333333-3333-4333-8333-333333333333"
    },
    "backer_count": 0,
    "my_seq_if_now": 1,
    "price_coins": "1.0000",
    "balance_before": "4900.0000",
    "balance_after": "4899.0000",
    "max_relay_payback_sapphires": "2.0000",
    "close_time": "2026-10-06T23:34:02.46058Z"
  },
  "confirm_token": "oc1.eyJhIjoiYmFja19vcGluaW9u…OjcAlET72O_MU5T4",
  "expires_at": "2026-09-08T23:40:33.745248Z"
}

max_relay_payback_sapphires is conditional, not a promise: it is the most this seat can receive if two more backers follow. If nobody follows, it pays nothing. Say so when you present it.

Show the summary to the user and get their explicit confirmation before calling the execute tool. The token is what proves a preview happened — it is not a substitute for asking.

When backing isn’t allowed

`reason`	Meaning
`OPINION_INACTIVE`	Hidden or not through moderation
`ALREADY_BACKED`	The owner already backed it — one backing per person; `my_seq_if_now` is their existing seat
`TOPIC_CLOSED`	Trading closed, so there is no quote
`INSUFFICIENT_BALANCE`	Not enough coins for this seat
`OPINION_BACK_FULL`	The price ladder is exhausted

Example prompts

“What would it cost to back that take?”
“How much do I pay to be the next backer?”

back_opinion · list_topic_opinions · list_my_backed_opinions

Getting Started

MCP Server

Platform

Parameters

Returns

When backing isn’t allowed

Example prompts

​Parameters

​Returns

​When backing isn’t allowed

​Example prompts

​Related

Parameters

Returns

When backing isn’t allowed

Example prompts

Related