# Core gRPC Execution
This page describes built-in test execution behavior in Rust CLI.
## What is built in
- gRPC transport and request execution
- unary and streaming call handling
- JSON request/response validation
- assertion execution
- TLS/mTLS support
- descriptor loading via reflection or `PROTO descriptor=<path>`
## Basic run example
```gctf
--- ADDRESS ---
localhost:9090
--- ENDPOINT ---
user.UserService/GetUser
--- REQUEST ---
{ "user_id": "123" }
--- RESPONSE ---
{ "user_id": "123" }
```
## Runtime controls
```bash
grpctestify tests/ --timeout 30
grpctestify tests/ --parallel 4
grpctestify tests/ --verbose
```
## RESPONSE inline options
```gctf
--- RESPONSE partial=true tolerance=0.1 unordered_arrays=true ---
{
"status": "ok"
}
```
## Notes
- `OPTIONS` section can override per-test runtime flags (`timeout`, `retry`, `retry-delay`, `no-retry`)
- `PROTO files=...` is not supported in native mode