Tool call · 5 checks · max 400 tokens · benched 2026-09-16
Anthropic models side by side on "Emit a weather tool call": Claude Haiku 4.5 scores 10/10; Claude Haiku 4.5 is the cheapest answer scoring 8+ at $0.28 per 1,000 runs. Outputs, checks, judge reasons, latency and cost.
System
You are a function-calling engine. Reply with JSON only, no prose, no code fences.
User
You have one tool:
{"name": "get_weather", "parameters": {"city": "string", "unit": "one of 'c' or 'f'"}}
Produce the tool call for this user message as a JSON object of the shape {"name": string, "arguments": object}.
User: What's it like in Lisbon right now? Fahrenheit please.Rubric for the judge: Exactly {"name":"get_weather","arguments":{"city":"Lisbon","unit":"f"}} with no extra keys or text.
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.
anthropic/claude-opus-5
144 in · 37 out · 7 words · checks 5/5
{"name": "get_weather", "arguments": {"city": "Lisbon", "unit": "f"}}Judge: Output exactly matches the required format with correct tool name, city, and unit parameters, no extra keys or commentary.
anthropic/claude-sonnet-5
144 in · 37 out · 7 words · checks 5/5
{"name": "get_weather", "arguments": {"city": "Lisbon", "unit": "f"}}Judge: Output exactly matches the required format with correct tool name, city, and unit parameters, no extra keys or commentary.
anthropic/claude-sonnet-4.6
114 in · 29 out · 7 words · checks 5/5
{"name": "get_weather", "arguments": {"city": "Lisbon", "unit": "f"}}Judge: Output exactly matches the required format with correct tool name, city, and unit parameters, no extra keys or commentary.
anthropic/claude-haiku-4.5
113 in · 34 out · 9 words · checks 5/5
```json
{"name": "get_weather", "arguments": {"city": "Lisbon", "unit": "f"}}
```Judge: Output exactly matches the required format with correct tool name, city, and unit parameters, no extra keys or commentary.
Tool call: Exactly {"name":"get_weather","arguments":{"city":"Lisbon","unit":"f"}} with no extra keys or text. The deterministic checks are json_valid, json_keys, regex, regex, regex.
If the judge's bar of 8/10 is good enough for you, Claude Haiku 4.5 at $0.28 per 1,000 runs. If you need the top score, Claude Haiku 4.5 at $0.28 per 1,000 runs.
Run it yourself
Re-run this prompt on Anthropic with your own OpenRouter key, or tweak the wording and see what changes.
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