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Tool call · 5 checks · max 400 tokens · benched 2026-09-16

Claude Opus 5 vs Claude Sonnet 5 vs Claude Sonnet 4.6 vs Claude Haiku 4.5 on pick the right tool of three

Anthropic models side by side on "Pick the right tool of three": Claude Haiku 4.5 scores 10/10; Claude Haiku 4.5 is the cheapest answer scoring 8+ at $0.37 per 1,000 runs. Outputs, checks, judge reasons, latency and cost.

The prompt every model received

System

You are a function-calling engine. Reply with JSON only, no prose, no code fences.

User

You have three tools:
1. {"name": "search_docs", "parameters": {"query": "string"}}
2. {"name": "create_ticket", "parameters": {"subject": "string", "body": "string"}}
3. {"name": "get_order_status", "parameters": {"order_id": "string"}}

Choose exactly one tool for the user message and produce the call as a JSON object of the shape {"name": string, "arguments": object}.

User: Where is my order A1029? It was supposed to arrive yesterday.

Rubric for the judge: Selects get_order_status with order_id A1029 and nothing else; does not open a ticket or search docs.

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
1.1s
Cost
$0.00178
Per 1,000
$1.78

202 in · 31 out · 5 words · checks 5/5

  • json_valid
  • json_keys
  • regex
  • regex
  • not_contains
{"name": "get_order_status", "arguments": {"order_id": "A1029"}}

Judge: Output correctly selects get_order_status with order_id A1029 in proper JSON format, matching the rubric requirements exactly.

Claude Sonnet 5

anthropic/claude-sonnet-5

10/10
Latency
1.1s
Cost
$0.00071
Per 1,000
$0.71

202 in · 31 out · 5 words · checks 5/5

  • json_valid
  • json_keys
  • regex
  • regex
  • not_contains
{"name": "get_order_status", "arguments": {"order_id": "A1029"}}

Judge: Output correctly selects get_order_status with order_id A1029 in proper JSON format, matching the rubric requirements exactly.

Claude Sonnet 4.6

anthropic/claude-sonnet-4.6

10/10
Latency
878ms
Cost
$0.00087
Per 1,000
$0.87

155 in · 27 out · 5 words · checks 5/5

  • json_valid
  • json_keys
  • regex
  • regex
  • not_contains
{"name": "get_order_status", "arguments": {"order_id": "A1029"}}

Judge: Output correctly selects get_order_status with order_id A1029 in proper JSON format, matching the rubric requirements exactly.

Claude Haiku 4.5

anthropic/claude-haiku-4.5

10/10
top judge scorecheapest scoring 8+
Latency
727ms
Cost
$0.00037
Per 1,000
$0.37

154 in · 44 out · 11 words · checks 5/5

  • json_valid
  • json_keys
  • regex
  • regex
  • not_contains
```json
{
  "name": "get_order_status",
  "arguments": {
    "order_id": "A1029"
  }
}
```

Judge: Output correctly selects get_order_status with order_id A1029, uses proper JSON format, and avoids unnecessary tools or commentary.

Frequently asked

What does this prompt test?

Tool call: Selects get_order_status with order_id A1029 and nothing else; does not open a ticket or search docs. The deterministic checks are json_valid, json_keys, regex, regex, not_contains.

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 $0.37 per 1,000 runs. If you need the top score, Claude Haiku 4.5 at $0.37 per 1,000 runs.

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