Beyond Wire Validation: Why MCP Servers Need Real Model Testing

Wire-level testing (curl, unit tests) only validates that your MCP server responds correctly—not that an AI model can actually use its tools. Real model testing reveals semantic-layer failures: tool selection errors, incorrect argument construction, and ambiguous descriptions that unit tests never catch. Since model behavior varies across platforms (Claude, GPT, Gemini), validating against actual models before deployment is essential for ensuring your tools work in production agent loops.