docs: use realtime function-call arguments in sample

[Rohan5commit]

Summary

• Updates the realtime tool-calling sample to use the function arguments returned by the model instead of a hard-coded location.
• Keeps the sample aligned with how a real tool invocation would be wired up.

Related issue

• Fixes [FEATURE REQ] Please improve the Realtime sample #535

Guideline alignment

• Single-file example improvement
• No generated files touched

Validation

• git diff --check
• Local dotnet build could not be run in this environment because the dotnet CLI is unavailable.

[Copilot]

Pull request overview

Updates the Realtime tool-calling example to consume the model-provided function arguments, making the sample closer to a real-world tool invocation flow (fixing #535).

Changes:

• Parse RealtimeFunctionCallItem.FunctionArguments as JSON to extract location and optional unit.
• Use parsed arguments when calling GetCurrentWeather(...) instead of a hard-coded location.

[Copilot]

GetProperty("location") will throw (with a generic KeyNotFoundException) if the model omits the location argument, so the subsequent null-coalescing InvalidOperationException message won’t be reached. Use TryGetProperty("location", out ...) (and validate ValueKind == String) so missing/invalid arguments produce the intended, actionable error message.

Suggested change

	string location = argumentsJson.RootElement.GetProperty("location").GetString()
	if (!argumentsJson.RootElement.TryGetProperty("location", out JsonElement locationElement)
	|| locationElement.ValueKind != JsonValueKind.String)
	{
	throw new InvalidOperationException("Tool call is missing a location.");
	}
	string location = locationElement.GetString()

[Copilot]

The log message uses functionCallItem.FunctionName, but the handler always invokes GetCurrentWeather(...) regardless of the reported function name. To keep the sample accurate (and avoid misleading output if additional tools are added later), either validate FunctionName == nameof(GetCurrentWeather) or dispatch based on FunctionName before parsing/handling arguments.

[jsquire]

Thank you for your contribution, @Rohan5commit, and your interest in improving the OpenAI developer experience. I think there's merit in the approach that you're demonstrating here. I find myself agreeing with the copilot comments and would ask that we address those before moving forward.

I'd also like to pull in @joseharriaga, @ShivangiReja, and @christothes for additional perspective here.