Tool Use / Function Calling Engineer Salary.
Across 30 U.S. cities.
$185,000
national median salary
$138,000 to $242,000. Last updated April 2026.
Highest Paying
$258,000
San Jose, CA
Best Purchasing Power
$190,000
Miami, FL
Lowest Paying
$163,000
St. Louis, MO
Salary data sourced from SEC filings, H-1B Labor Condition Applications (DOL), Bureau of Labor Statistics Occupational Employment and Wage Statistics, and aggregated job postings across 50+ platforms. Ranges reflect 25th to 75th percentile for full-time positions. Cost-of-living adjustments use Bureau of Economic Analysis Regional Price Parities (2025 index). Last updated April 2026.
The average Tool Use / Function Calling Engineer salary in the United States is $185,000 in 2026, with the full range spanning $138,000 at the 25th percentile to $242,000 at the 75th. San Jose pays the most at $258,000, while Miami offers the best purchasing power after cost-of-living adjustments. Compensation scales with the complexity and reliability of tool integration systems built.
Tool Use / Function Calling Engineer salary by city
What you should know
Compensation scales with the complexity and reliability of tool integration systems built. Engineers who can design robust function calling frameworks with error recovery and multi-step planning earn premiums. Experience with multiple LLM providers and enterprise API ecosystems drives salaries 10% to 18% above median.
Junior tool integration engineers start near $138,000 building basic function schemas. Mid-level engineers designing robust multi-tool orchestration earn $183,000 to $210,000. Principal engineers architecting enterprise tool-use platforms reach $242,000 to $290,000.
Equity at AI platform companies is a significant compensation component. Performance bonuses of 12% to 18% are standard, with some roles offering developer ecosystem growth bonuses tied to platform adoption metrics.