Agentic AI Engineer, .NET, C#

Client: Global Technology Leader - NASDAQ Listed Location: Hybrid - Bristol / 3 Days Per Week Duration: 6 months + Intention to extend (Greenfield Multi-Year Programme) Day rate: £500 - Inside IR35 Start date: ASAP Our client, a global leader in software systems, is building AI agents that generate production .NET code under developer supervision. The goal of this greenfield is a spec-driven pipeline where a specification and technical plan drive what the agent builds, and a developer reviews and validates the output at every stage before it ships. We are looking for a contractor who has built and shipped AI agents in production and who brings a strong .NET background. This is a hands-on engineering role with scope to set the technical direction and bring the wider team up to speed on the approach. What you will do: Design and build agents that produce production-grade .NET code. Implement a spec-driven development workflow (spec, plan, tasks, implement), using Spec Kit. Build review and approval gates so developers can verify and correct agent output before it is merged. Integrate tools and data sources into the agents via MCP (Model Context Protocol). Set up evaluation, guardrails and tests to catch incorrect output early. Work alongside engineering team's and upskill them on agentic patterns and the spec-driven approach. Essential experience: Proven track record building and shipping AI agents in production, including tool calling, orchestration and multi-step workflows. Prototype-only experience will not be enough. Strong .NET and C# background (.NET 8/9, ASP.NET Core). Hands-on with a .NET-native agent framework, such as Microsoft Agent Framework or Semantic Kernel. Experience building agents whose output is code, with a clear focus on validating and verifying correctness. Familiarity with spec-driven development, ideally Spec Kit. Experience integrating tools via MCP. Designing human-in-the-loop review and approval gates within agent workflows. Reasonable Adjustments: Respect and equality are core values to us. We are proud of the diverse and inclusive community we have built, and we welcome applications from people of all backgrounds and perspectives. Our success is driven by our people, united by the spirit of partnership to deliver the best resourcing solutions for our clients. If you need any help or adjustments during the recruitment process for any reason , please let us know when you apply or talk to the recruiters directly so we can support you.