Improve a prompt

⚠️

Preview — this feature is being built; the design below is the spec.

POST https://app.syntic.ai/v1/prompts/improve

Rewrite an existing prompt against feedback you give and, optionally, examples where it went wrong. The response returns the new prompt and a list of what changed and why, so you can review the diff before adopting it, then compare both with an evaluation run.

For how this fits into a full workflow, see Prompt generator and improver.

Headers

Header	Required	Value
`Authorization`	Yes	`Bearer <key>`: a private inference key (`sk_live_...`). See Authentication.
`syntic-beta`	Yes, while in preview	`prompt-tools-2026-12-01`. Without it the call fails with `400 beta_required`. See Versioning.
`Content-Type`	Yes	`application/json`

Body parameters

Parameter	Type	Required	Notes
`system`	string	Yes	The current system prompt.
`messages`	array	No	The current user template.
`feedback`	string	Yes	What should change, up to 2,000 characters.
`failing_examples`	array	No	Up to 10 `{input, output, expected}` cases.
`target_model`	string	No

Response

200 OK, Content-Type: application/json

{
  "system": "You answer customer questions for Acme's online shop.\n\nRules:\n- Keep replies under 120 words.\n- Only state policies listed in <policies>. If a question is not covered, say you will pass it to a colleague.\n…",
  "changes": [
    {
      "change": "Added a length limit",
      "reason": "Feedback: answers too long."
    },
    {
      "change": "Restricted claims to listed policies",
      "reason": "Failing example promised a refund that is not offered."
    }
  ],
  "usage": {
    "input_tokens": 2210,
    "output_tokens": 712
  }
}

Field	Type	Description
`changes`	array	Each edit with the reason for it.

Examples

curl -sS "https://app.syntic.ai/v1/prompts/improve" \
  -H "Authorization: Bearer $SYNTIC_API_KEY" \
  -H "syntic-beta: prompt-tools-2026-12-01" \
  -H "Content-Type: application/json" \
  -d '{
      "system": "You are a helpful support agent. Answer the customer.",
      "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
      "failing_examples": [
        {
          "input": "Can I return a sale item?",
          "output": "Of course! We'll refund you in full…",
          "expected": "Sale items are exchange-only within 14 days."
        }
      ]
    }'

import os
 
import requests
 
resp = requests.post(
    "https://app.syntic.ai/v1/prompts/improve",
    headers={
        "Authorization": f"Bearer {os.environ['SYNTIC_API_KEY']}",
        "syntic-beta": "prompt-tools-2026-12-01",
    },
    json={
        "system": "You are a helpful support agent. Answer the customer.",
        "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
        "failing_examples": [
            {
                "input": "Can I return a sale item?",
                "output": "Of course! We'll refund you in full…",
                "expected": "Sale items are exchange-only within 14 days."
            }
        ]
    },
    timeout=60,
)
data = resp.json()
if not resp.ok:
    raise RuntimeError(f"{resp.status_code} {data['error']['code']}: {data['error']['message']}")
print(data)

const res = await fetch('https://app.syntic.ai/v1/prompts/improve', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.SYNTIC_API_KEY}`,
    'syntic-beta': 'prompt-tools-2026-12-01',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "system": "You are a helpful support agent. Answer the customer.",
    "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
    "failing_examples": [
      {
        "input": "Can I return a sale item?",
        "output": "Of course! We'll refund you in full…",
        "expected": "Sale items are exchange-only within 14 days."
      }
    ]
  }),
})
const text = await res.text()
const data = text ? JSON.parse(text) : null
if (!res.ok) throw new Error(`${res.status} ${data.error.code}: ${data.error.message}`)
console.log(data ?? res.status)

package main
 
import (
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"
)
 
func main() {
	body := strings.NewReader(`{
  "system": "You are a helpful support agent. Answer the customer.",
  "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
  "failing_examples": [
    {
      "input": "Can I return a sale item?",
      "output": "Of course! We'll refund you in full…",
      "expected": "Sale items are exchange-only within 14 days."
    }
  ]
}`)
	req, err := http.NewRequest("POST", "https://app.syntic.ai/v1/prompts/improve", body)
	if err != nil {
		panic(err)
	}
	req.Header.Set("Authorization", "Bearer "+os.Getenv("SYNTIC_API_KEY"))
	req.Header.Set("syntic-beta", "prompt-tools-2026-12-01")
	req.Header.Set("Content-Type", "application/json")
 
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer resp.Body.Close()
 
	out, _ := io.ReadAll(resp.Body)
	if resp.StatusCode >= 300 {
		panic(fmt.Sprintf("%d: %s", resp.StatusCode, out))
	}
	fmt.Println(string(out))
}

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
 
public class Example {
    public static void main(String[] args) throws Exception {
        String body = """
            {
              "system": "You are a helpful support agent. Answer the customer.",
              "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
              "failing_examples": [
                {
                  "input": "Can I return a sale item?",
                  "output": "Of course! We'll refund you in full…",
                  "expected": "Sale items are exchange-only within 14 days."
                }
              ]
            }
            """;
        HttpRequest request = HttpRequest.newBuilder(URI.create("https://app.syntic.ai/v1/prompts/improve"))
            .header("Authorization", "Bearer " + System.getenv("SYNTIC_API_KEY"))
            .header("syntic-beta", "prompt-tools-2026-12-01")
            .header("Content-Type", "application/json")
            .method("POST", HttpRequest.BodyPublishers.ofString(body))
            .build();
        HttpResponse<String> response = HttpClient.newHttpClient()
            .send(request, HttpResponse.BodyHandlers.ofString());
        if (response.statusCode() >= 300) {
            throw new RuntimeException(response.statusCode() + ": " + response.body());
        }
        System.out.println(response.body());
    }
}

using System.Net.Http.Headers;
using System.Text;
 
using var http = new HttpClient();
using var request = new HttpRequestMessage(new HttpMethod("POST"), "https://app.syntic.ai/v1/prompts/improve");
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", Environment.GetEnvironmentVariable("SYNTIC_API_KEY"));
request.Headers.Add("syntic-beta", "prompt-tools-2026-12-01");
request.Content = new StringContent("""
    {
      "system": "You are a helpful support agent. Answer the customer.",
      "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
      "failing_examples": [
        {
          "input": "Can I return a sale item?",
          "output": "Of course! We'll refund you in full…",
          "expected": "Sale items are exchange-only within 14 days."
        }
      ]
    }
    """, Encoding.UTF8, "application/json");
 
using var response = await http.SendAsync(request);
var text = await response.Content.ReadAsStringAsync();
if (!response.IsSuccessStatusCode) throw new Exception($"{(int)response.StatusCode}: {text}");
Console.WriteLine(text);

<?php
$body = <<<'JSON'
{
  "system": "You are a helpful support agent. Answer the customer.",
  "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
  "failing_examples": [
    {
      "input": "Can I return a sale item?",
      "output": "Of course! We'll refund you in full…",
      "expected": "Sale items are exchange-only within 14 days."
    }
  ]
}
JSON;
 
$ch = curl_init('https://app.syntic.ai/v1/prompts/improve');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer ' . getenv('SYNTIC_API_KEY'),
        'syntic-beta: prompt-tools-2026-12-01',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => $body,
]);
$response = curl_exec($ch);
$status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
curl_close($ch);
 
if ($status >= 300) {
    throw new RuntimeException("$status: $response");
}
print_r(json_decode($response, true) ?? $status);

require "json"
require "net/http"
require "uri"
 
uri = URI("https://app.syntic.ai/v1/prompts/improve")
req = Net::HTTP::Post.new(uri)
req["Authorization"] = "Bearer #{ENV.fetch('SYNTIC_API_KEY')}"
req["syntic-beta"] = "prompt-tools-2026-12-01"
req["Content-Type"] = "application/json"
req.body = <<~'JSON'
  {
    "system": "You are a helpful support agent. Answer the customer.",
    "feedback": "Answers are too long and sometimes promise refunds we do not offer.",
    "failing_examples": [
      {
        "input": "Can I return a sale item?",
        "output": "Of course! We'll refund you in full…",
        "expected": "Sale items are exchange-only within 14 days."
      }
    ]
  }
JSON
 
res = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(req) }
raise "#{res.code}: #{res.body}" unless res.is_a?(Net::HTTPSuccess)
puts res.body.empty? ? res.code : JSON.pretty_generate(JSON.parse(res.body))

Errors

Errors use the error envelope and carry a request_id. Codes specific to this operation:

Status	`type`	`code`	When
400	`invalid_request_error`	`beta_required`	The `syntic-beta` header is missing.
401	`authentication_error`	`invalid_api_key`	The key is missing, unknown, revoked or expired.
429	`rate_limit_error`	`rate_limited`	Too many requests; wait for `Retry-After`. See Rate-limit headers.

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