OpenAI launched GPT-5 today, and one feature stands out: instruction following and agentic tool use.
GPT-5 + Unified MCP Server: Perfect Match
We tested GPT-5 with our unified MCP server connecting 40+ tools, and the results are remarkable. Unlike GPT-4o, which hallucinates when orchestrating multiple tools, GPT-5 reliably:
- Follows complex multi-step instructions across unified tool sets
- Maintains context throughout extended workflows
- Intelligently selects the right tools from the unified server
- Recovers gracefully from tool failures
GPT-5 Function Calling Performance
The Tau2-bench results show GPT-5's superior function calling capabilities across different domains:
GPT-5 significantly outperforms both OpenAI o3 and GPT-4o in function calling accuracy across airline, retail, and telecom domains, especially when using thinking capabilities.
Why Unified MCP Server Works Better with GPT-5
GPT-4o's hallucination issues made it unreliable for production MCP workflows. GPT-5 changes everything:
GPT-4o Problems:
- Fabricates tool responses
- Loses workflow state
- Incorrect tool chaining
GPT-5 + Unified MCP Server:
- Seamless tool orchestration through single endpoint
- Persistent context across all connected tools
- Reliable multi-tool workflows via unified interface
This breakthrough makes GPT-5 + unified MCP server the perfect combination for enterprise deployments. Experience superior agentic tool use with our unified MCP server architecture.