Why do SEO agencies ask for access to our Google Search Console and Google Tag Manager?

[NBJ_SM]

What do they need GTM for? And what is the use case for setting up Google Search Console?

[jasongmcmahon]

The simple answer I use in response to my clients is that GTM is for setting up more accurate tracking & Google Search Console (GSC) is for more accurate reporting.

For a more in-depth explanation, Moz has some useful articles

• https://moz.com/blog/an-introduction-to-google-tag-manager
• https://moz.com/blog/a-beginners-guide-to-the-google-search-console

Also, I recommend that you ask the agencies you're talking to what the track, measure & report on.

[triveraseo]

GTM allows a great deal of tracking capabilities without having to use a programmer to modify your code. Better tracking equals the ability to make better decisions and determine what is and isn't work.  Google Search Console keeps an eye on the "heartbeat" of your website and helps you see any issues that Google may have with the technical aspect of your website.  Both free and both great tools. The better question to ask would be, "What should I do if my agency DOESN'T ask for or use these tools?"

If an agency isn't tracking performance and using that data to continually improve, I'd be questioning the agency.