Claude Sonnet 4.6 vs Grok 4 for Tool Calling
Claude Sonnet 4.6 is the winner for Tool Calling in our testing. Sonnet scores 5 on our tool_calling benchmark versus Grok 4, and Sonnet is ranked #1 for this task (rank 1 of 52) while Grok is rank 18 of 52. Sonnet's win is supported by higher agentic_planning (5 vs 3) and safety_calibration (5 vs 2), which in our tests translated to more reliable function selection, argument sequencing, and safer refusals. Grok 4 remains a solid option (tool_calling 4) with strengths in constrained_rewriting (4) and equal structured_output (4), and its model description notes support for parallel tool calling — a practical advantage in some workloads.
anthropic
Claude Sonnet 4.6
Benchmark Scores
External Benchmarks
Pricing
Input
$3.00/MTok
Output
$15.00/MTok
modelpicker.net
xai
Grok 4
Benchmark Scores
External Benchmarks
Pricing
Input
$3.00/MTok
Output
$15.00/MTok
modelpicker.net
Task Analysis
Tool Calling demands correct function selection, precise argument values and types, correct sequencing of calls, robust error recovery, and reliable formatted outputs (per our benchmark description: "Function selection, argument accuracy, sequencing"). In our testing the primary signal is the tool_calling score: Claude Sonnet 4.6 = 5, Grok 4 = 4. Supporting proxies explain the gap: Sonnet scores 5 on agentic_planning and 5 on safety_calibration, indicating better goal decomposition, failure recovery, and safer permission/refusal behavior when calling sensitive APIs. Both models tie on structured_output (4), so JSON/schema compliance is comparable. Grok's advantages in constrained_rewriting (4 vs Sonnet's 3) and its model description (parallel tool calling support) matter when you need compact arguments or concurrent call patterns, but they didn't outweigh Sonnet's higher end-to-end tool orchestration and safety performance in our tests.
Practical Examples
Where Claude Sonnet 4.6 shines (based on our scores):
- Multi-step API orchestration with recovery: Sonnet 5 (tool_calling) + agentic_planning 5 — fewer sequencing errors and better fallback plans when calls fail.
- Safety-sensitive integrations: Sonnet safety_calibration 5 — more consistent safe refusals and correct permissions handling when APIs expose sensitive actions.
- Large-session tool chains requiring deep context: Sonnet has a 1,000,000 token window (payload) and long_context 5, useful when tool decisions depend on long histories. Where Grok 4 shines (based on our scores and description):
- Compact, encoded argument patterns: constrained_rewriting 4 helps fit arguments into tight schemas or token budgets.
- Parallel tool invocation workflows: Grok's description explicitly notes support for parallel tool calling — valuable for concurrent API calls or batched tool execution.
- Mixed media tool inputs: Grok modality includes file->text (payload), which can simplify tools that consume files as part of the call flow. Concrete numeric differences to ground the examples: Sonnet tool_calling 5 vs Grok 4 (one-point gap), agentic_planning 5 vs 3, safety_calibration 5 vs 2, structured_output tied at 4. Sonnet rank #1 vs Grok rank #18 for tool calling in our tests.
Bottom Line
For Tool Calling, choose Claude Sonnet 4.6 if you need the most reliable end-to-end function selection, sequencing, failure recovery, and safety (Sonnet: tool_calling 5, agentic_planning 5, safety_calibration 5; rank #1). Choose Grok 4 if you prioritize parallel tool invocation, tighter argument packing or file-based inputs (Grok: tool_calling 4, constrained_rewriting 4, model notes parallel tool calling; rank #18).
How We Test
We test every model against our 12-benchmark suite covering tool calling, agentic planning, creative problem solving, safety calibration, and more. Each test is scored 1–5 by an LLM judge. Read our full methodology.