Model Behaviour Architect, General Agents

Mistral AI; Greater London; On-site; GBP 110,000 - 170,000; Full time

Benefits offered by this job

Healthcare

Parental leave

Retirement plans

Relocation support

Wellness programs

Meal and transportation allowances

Job summary

Mistral AI is seeking a Model Behaviour Architect to define and measure how large language models interact with tools, invoke functions, and orchestrate workflows on the General Agents team. You will ensure models perform accurate, reliable tool use and robust multi-step orchestration.

Collaborating with our Science team, you will turn research insights into concrete evaluation pipelines and guidelines, shaping what 'good' looks like for function calling and enabling greater autonomy and

Qualifications

• Strong knowledge of API design and JSON Schema.
• Experience with LLM agents, reasoning, planning, and multi-step tool use.
• Experience training or optimizing model behaviour for real-world apps.
• Proven ability to build scalable evaluation frameworks.
• Ability to work in dynamic, technically complex environments.

Responsibilities

• Identify opportunities to improve function calling and tool use in models.
• Gather feedback to scope enhancements for model behaviour.
• Design evaluations, data guidelines, and synthetic tool environments.
• Address edge cases and perform rigorous testing.
• Develop evaluation pipelines for model candidates' function-calling.
• Collaborate with AI Scientists to align behaviour with research insights.

Skills

API design & JSON Schema

LLM agents & tool use

Reasoning & planning

Model behaviour tuning

Evaluation frameworks

Job description

About Mistral

Mistral provides full-stack AI solutions: from frontier models to developer tools, applications, and compute. We partner with enterprises tackling the hardest problems—across high-stakes industries like finance, manufacturing, defense, healthcare, and the public sector—co-creating customized AI systems that they can run on their terms.

We are a dynamic, collaborative team passionate about AI and its potential to transform society. Our diverse workforce thrives in competitive environments and is committed to driving innovation. Our teams are distributed between Europe, North America, Asia and the Middle East. We are creative, low-ego and team-spirited.

The Role

As a Model Behaviour Architect on the General Agents team, you will define and measure how large language models interact with tools, invoke functions, and orchestrate complex workflows. This role exists to ensure our models excel at accurate, reliable, and intelligent tool use, from precise parameter selection to multi-step orchestration and error recovery. You will collaborate closely with our Science team to shape what "good" looks like for function calling, turning research insights into best-in-class model behaviour.
Your work will directly impact the capabilities of Mistral’s models, enabling them to solve real-world problems with greater autonomy and precision.

What You Will Do

• Interact with models to identify opportunities for improving function calling and tool use behaviour.

• Gather internal and external feedback to scope and prioritise areas for enhancement.

• Design and implement evaluations, data guidelines, and synthetic tool environments and APIs.

• Address edge cases such as malformed arguments, hallucinated functions, and incorrect tool selection through rigorous testing.

• Develop robust evaluation pipelines to assess the function-calling capabilities of model candidates.

• Collaborate with AI Scientists to align model behaviour with research insights and real-world needs.

What We're Looking For

• Deep understanding of API design, structured outputs, and schema specification (e.g., JSON Schema), or expertise in engineering and code behaviour, or experience with LLM agents, including reasoning, planning, and multi-step tool use.

• Prior knowledge in training and optimising model behaviour for real-world applications.

• Expertise in building robust, scalable evaluation frameworks for AI systems.

• Ability to thrive in dynamic, technically complex environments and deliver innovative solutions.

• Track record of solving open-ended challenges with creative, out-of-the-box approaches.

What We Offer

We offer a comprehensive benefits package designed to support your well-being, growth, and work-life balance. Benefits vary by country and may include healthcare coverage, parental leave, retirement plans, relocation support, wellness programs, meal and transportation allowances, and other location-specific perks.

For the most up-to-date details on benefits available in your location, please refer to our Benefits page.

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