---
title: "Reply drafting"
method: POST
path: "/v1/reply"
tags: ["Reply drafting"]
---

# Reply drafting

`POST /v1/reply`

## Request

- Base URL: `https://api.thecompound.tech`
- URL: `https://api.thecompound.tech/v1/reply`
- Auth: HTTP bearer

ParseRail turns a customer thread and your context into a ready-to-send reply. The reply uses the requested tone and includes an internal note for the agent.

Cost: 5 credits ($0.05) — charged only on success.

## Headers

- `ParseRail-Dry-Run` '1' | 'true'
- `Idempotency-Key` string

## Request body

- object
  - `thread` string, required: Provide the email/ticket thread with the newest message last.
  - `context` string: Provide the policies, KB extracts, and account facts that the reply may use.
  - `tone` 'professional' | 'friendly' | 'apologetic' | 'firm'
  - `goal` string: State what the reply should achieve, e.g. "offer refund, keep them".
  - `senderName` string: Sign-off name.

## Response `200`

The call succeeded. The response contains result fields and a usage envelope. With `ParseRail-Dry-Run: 1` the body is a DryRun object instead.

- union
  - object
    - `reply` string, required: Ready to send.
    - `subject` string, nullable
    - `internalNote` string, nullable: Provide caveats and things for the human agent to verify.
    - `usage` Usage, required
      - `credits` integer, required: Credits burned by this call.
      - `balanceRemaining` integer, required: Wallet balance after the charge.
  - DryRun: A dry run: auth, the per-key throttle, body validation and the balance precheck ran. No model ran and nothing was charged.
    - `dryRun` true, required
    - `valid` true, required: The body passed validation. An invalid body returns 400 instead.
    - `endpoint` string, required
    - `wouldCharge` integer, required: Credits a successful live call would charge.
    - `balance` integer, required: Your wallet balance now.
    - `liveStatus` 200 | 202 | 402, required: The status a live call with this body would get: 402 when the balance or the key's monthly cap cannot cover it, 202 for `async: true`, else 200.
    - `keyCapRemaining` integer: Present when the key carries a monthly cap: credits left under it this month.
    - `usage` Usage, required
      - `credits` integer, required: Credits burned by this call.
      - `balanceRemaining` integer, required: Wallet balance after the charge.
    - `requestId` string, required

## Other responses

- `400`: Invalid request body.
- `401`: Missing or invalid API key.
- `402`: `insufficient_credits`: the balance cannot cover the call. `spend_cap_reached`: the key has reached its monthly cap. Nothing is charged.
- `429`: Rate limit exceeded.

---

[API](https://skmtc.dev/thecompound/apis/parserail.md) · [All operations](https://skmtc.dev/thecompound/apis/parserail/llms.txt) · [OpenAPI document](https://skmtc.dev/thecompound/apis/parserail/revisions/7895a3b7812b?raw)