gcf.fastmcp.GcfResponseMiddleware now uses GCF only when the wire is smaller than the JSON it would replace, so a small tool result is never enlarged. It already required a verified lossless round-trip against the input; this adds the never-grow size guard, completing the never-grow + verify-against-input contract used across the ecosystem's MCP integrations. The zero-dependency core is unchanged.
Full changelog: https://github.com/blackwell-systems/gcf-python/blob/main/CHANGELOG.md