Insights from the Leon van Zyl episode “OpenCode + Ollama: Claude Code Failed. This Works. (Full Setup)”, published June 4, 2026.
In "OpenCode + Ollama: Claude Code Failed. This Works. (Full Setup)" (Leon van Zyl, June 2026), claude Code's heavy system prompts often overwhelm local hardware, causing hallucinations and tool failures. By using OpenCode as a lightweight harness with Ollama, you can run powerful open-source models like Qwen 2.5…
In "OpenCode + Ollama: Claude Code Failed. This Works. (Full Setup)", This represents the non-productive tokens consumed by system prompts and tool definitions. In local setups, this significantly reduces the space available for actual code logic, leading to degraded model performance.
In "OpenCode + Ollama: Claude Code Failed. This Works. (Full Setup)", By segmenting a project into phase files, you keep the agent's context window clean and focused on immediate goals, which prevents hallucination and logic errors in complex codebases.
In "OpenCode + Ollama: Claude Code Failed. This Works. (Full Setup)", Not all frameworks are tuned for local models. A 'harness' needs to be lightweight enough to allow the model to interpret instructions clearly, otherwise the system tools will drown out the actual coding tasks.
Claude Code's heavy system prompts often overwhelm local hardware, causing hallucinations and tool failures. By using OpenCode as a lightweight harness with Ollama, you can run powerful open-source models like Qwen 2.5 locally while maintaining high instruction-following performance for complex coding tasks.
Topics: AI Agents, Local LLMs, Coding Productivity, Ollama, OpenCode