Grok 4.6 vs Grok 4.5 vs Grok 4.20 vs Grok 4.3 on emit a calendar tool call
xAI models side by side on "Emit a calendar tool call": Grok 4.3 scores 10/10; Grok 4.3 is the cheapest answer scoring 8+ at $1.28 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 one tool:
{"name": "create_event", "parameters": {"title": "string", "start": "ISO 8601 date-time without timezone, e.g. 2026-01-31T09:00", "duration_minutes": "integer", "attendees": "array of email strings"}}
Produce the tool call for this user message as a JSON object of the shape {"name": string, "arguments": object}.
User: Book a 45-minute design review with [email protected] and [email protected] on 2 October 2026 at 3pm.
Rubric for the judge: Correct tool name, ISO start 2026-10-02T15:00, integer duration 45, both attendees in an array, a sensible title.
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.
Grok 4.6
x-ai/grok-4.6
10/10
Latency
520ms
Cost
$0.00237
Per 1,000
$2.37
358 in · 307 out (249 reasoning) · 13 words · checks 7/7
Judge: All rubric criteria met: correct tool name, proper ISO 8601 start datetime, integer duration of 45 minutes, both attendees in array format, and sensible title.
Grok 4.5
x-ai/grok-4.5
10/10
Latency
286ms
Cost
$0.00157
Per 1,000
$1.57
358 in · 178 out (120 reasoning) · 13 words · checks 7/7
Judge: All rubric criteria met: correct tool name, proper ISO 8601 start datetime, integer duration of 45 minutes, both attendees in array format, and sensible title.
Grok 4.20
x-ai/grok-4.20
10/10
Latency
261ms
Cost
$0.00142
Per 1,000
$1.42
330 in · 457 out (403 reasoning) · 13 words · checks 7/7
Judge: All rubric criteria met: correct tool name, proper ISO 8601 start datetime, integer duration of 45 minutes, both attendees in array format, and sensible title.
Grok 4.3
x-ai/grok-4.3
10/10
top judge scorecheapest scoring 8+
Latency
268ms
Cost
$0.00128
Per 1,000
$1.28
336 in · 425 out (361 reasoning) · 17 words · checks 7/7
Judge: All rubric requirements met: correct tool name, ISO start datetime 2026-10-02T15:00, integer duration 45, both attendees in array, and sensible title 'design review'.
Frequently asked
▸What does this prompt test?
Tool call: Correct tool name, ISO start 2026-10-02T15:00, integer duration 45, both attendees in an array, a sensible title. The deterministic checks are json_valid, json_keys, regex, contains, regex, contains, contains.
▸Which model should I pick for this task?
If the judge's bar of 8/10 is good enough for you, Grok 4.3 at $1.28 per 1,000 runs. If you need the top score, Grok 4.3 at $1.28 per 1,000 runs.
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