Claude Opus 5 vs Claude Sonnet 5 vs Claude Sonnet 4.6 vs Claude Haiku 4.5 on event announcement to structured json
Anthropic models side by side on "Event announcement to structured JSON": Claude Haiku 4.5 scores 10/10; Claude Haiku 4.5 is the cheapest answer scoring 8+ at $0.52 per 1,000 runs. Outputs, checks, judge reasons, latency and cost.
The prompt every model received
System
You are a data extraction engine. Reply with JSON only, no prose, no code fences.
User
Return one JSON object with keys title (string), date (YYYY-MM-DD), start_time (24-hour HH:MM), location (string), attendees (integer). Use only facts stated in the announcement.
Announcement: Join us for the Autumn Data Meetup on Tuesday 3 November 2026. Doors open at 2 pm and talks start at 2:30 pm at The Loft, 14 Harbour Street. We have confirmed 48 attendees so far and can take up to 60.
Rubric for the judge: Correctly picks the talk start (14:30, not doors), ISO date, integer attendees 48, and a sensible title and location.
Side by side
Every cell is one OpenRouter call at temperature 0 with the prompt's token cap and reasoning effort "low" where the model supports it. Cost is usage × the catalogue rate in models.json. Quality is one judge call to anthropic/claude-haiku-4.5 against the prompt's rubric, cached per prompt version.
Claude Opus 5
anthropic/claude-opus-5
10/10
Latency
2.1s
Cost
$0.00250
Per 1,000
$2.50
195 in · 61 out · 7 words · checks 5/5
✓json_valid
✓json_keys
✓contains
✓contains
✓regex
{"title":"Autumn Data Meetup","date":"2026-11-03","start_time":"14:30","location":"The Loft, 14 Harbour Street","attendees":48}
Judge: All fields correctly extracted: title matches announcement, date in ISO format (2026-11-03), start_time correctly uses talk start time (14:30) not door opening, location fully specified, and attendees set to confirmed count (48).
Claude Sonnet 5
anthropic/claude-sonnet-5
10/10
Latency
1.2s
Cost
$0.00105
Per 1,000
$1.05
195 in · 66 out · 9 words · checks 5/5
✓json_valid
✓json_keys
✓contains
✓contains
✓regex
```json
{"title":"Autumn Data Meetup","date":"2026-11-03","start_time":"14:30","location":"The Loft, 14 Harbour Street","attendees":48}
```
Judge: All fields correctly extracted: title matches announcement, date in ISO format (2026-11-03), start_time correctly uses talk start time (14:30) not doors open, location fully specified, and attendees set to confirmed count (48).
Claude Sonnet 4.6
anthropic/claude-sonnet-4.6
4/10
Latency
897ms
Cost
$0.00132
Per 1,000
$1.32
149 in · 58 out · 16 words · checks 4/5
✓json_valid
✓json_keys
✓contains
✕contains
✓regex
{"title": "Autumn Data Meetup", "date": "2026-11-03", "start_time": "14:00", "location": "The Loft, 14 Harbour Street", "attendees": 48}
Judge: Correctly extracted title, date, location, and attendees, but start_time is 14:00 (doors open) instead of 14:30 (talks start) as specified in the rubric.
Claude Haiku 4.5
anthropic/claude-haiku-4.5
10/10
top judge scorecheapest scoring 8+
Latency
776ms
Cost
$0.00052
Per 1,000
$0.52
148 in · 75 out · 20 words · checks 5/5
✓json_valid
✓json_keys
✓contains
✓contains
✓regex
```json
{
"title": "Autumn Data Meetup",
"date": "2026-11-03",
"start_time": "14:30",
"location": "The Loft, 14 Harbour Street",
"attendees": 48
}
```
Judge: All fields correctly extracted: title matches announcement, date in ISO format (2026-11-03), start_time correctly uses talk start time (14:30 not doors open 14:00), location fully specified, and attendees set to confirmed count (48).
Frequently asked
▸What does this prompt test?
Extract JSON: Correctly picks the talk start (14:30, not doors), ISO date, integer attendees 48, and a sensible title and location. The deterministic checks are json_valid, json_keys, contains, contains, regex.
▸Which model should I pick for this task?
If the judge's bar of 8/10 is good enough for you, Claude Haiku 4.5 at $0.52 per 1,000 runs. If you need the top score, Claude Haiku 4.5 at $0.52 per 1,000 runs.
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