WEBVTT 00:00.160 --> 00:07.840 And welcome to week six, day two, the day in which we get to build our own MCP client and MCP server. 00:08.040 --> 00:11.480 MCP being the USB-C for I. 00:12.360 --> 00:17.680 And I've just realized this picture actually shows USB a for for I, I imagine a bunch of people are 00:17.680 --> 00:20.360 going to point this out to me from the last time I showed this picture. 00:20.600 --> 00:21.200 Sorry about that. 00:21.200 --> 00:28.280 But, you know, it's it's this this picture is showing what what it could be without having MCP, which 00:28.280 --> 00:30.960 is of course our USB-C for I. 00:31.480 --> 00:34.280 Anyways, moving on, let's get to it. 00:34.320 --> 00:39.920 As usual with these new things, I like to bring up the same material a couple of times to really drive 00:39.960 --> 00:40.960 the point home. 00:41.160 --> 00:48.640 The three pieces of the puzzle of MCP the host, which is the app like Cloud Desktop or our own agent 00:48.680 --> 00:55.200 platform, the MCP client, which is inside the host, and there's an MCP client for every MCP server. 00:55.480 --> 01:03.920 And the MCP server is one particular grouping of tools, contexts and prompts made by somebody that 01:04.020 --> 01:05.580 we can reuse. 01:05.820 --> 01:12.420 And I gave the example there of using fetch as a way of running a headless browser. 01:12.900 --> 01:13.340 Okay. 01:13.380 --> 01:15.460 And then also a reminder the architecture. 01:15.460 --> 01:19.180 This is a more busy diagram, but hopefully one that's quite familiar to you now. 01:19.460 --> 01:23.780 So the host the blue box there runs a number of MCP clients. 01:23.900 --> 01:27.020 And I talked about the three different approaches. 01:27.180 --> 01:34.940 The first of them that that first yellow box is where an MCP client talks to an MCP server that is running 01:35.140 --> 01:41.380 locally on that box, although in a different process that was typically sort of spawned by the MCP 01:41.380 --> 01:42.140 client. 01:42.140 --> 01:46.020 And they connect over standard input and output for that process. 01:46.060 --> 01:49.980 And it's known as a studio or stdio connection. 01:50.660 --> 01:54.140 And the second yellow box is very similar. 01:54.140 --> 01:59.020 Another MCP client running in the host connecting to an MCP server in a different process on the same 01:59.020 --> 01:59.500 box. 01:59.500 --> 02:04.820 But it's just to show that there will frequently be cases where that MCP server is in fact connecting 02:04.860 --> 02:07.550 to a to a remote server to carry out an API. 02:07.790 --> 02:10.710 Just that's how that's what the code does in that MCP. 02:10.750 --> 02:11.070 Server. 02:11.070 --> 02:13.790 Maybe it calls out to Google's weather API. 02:13.830 --> 02:15.470 Maybe it calls out to slack. 02:15.630 --> 02:18.830 Whatever it's doing, it happens to have an internet connection. 02:18.830 --> 02:20.510 So basically the two. 02:20.550 --> 02:23.150 First two orange boxes are basically the same thing. 02:23.150 --> 02:24.150 Just one of them happens to. 02:24.190 --> 02:25.110 Use the internet. 02:25.590 --> 02:28.270 But the third yellow box is a different architecture. 02:28.270 --> 02:34.950 And this is where you have an MCP client that's calling out to an MCP server running remotely. 02:34.950 --> 02:39.350 And there you would have to use the SSE type of transport. 02:39.550 --> 02:47.350 The server side events, which allows for it would do an HTTP push sorry post to send the message out, 02:47.390 --> 02:53.670 and then it would receive back the information streamed back using the SSE approach. 02:53.870 --> 03:00.590 And this is less common generally in MCP land, at least as of now, it's not so common, but we we 03:00.590 --> 03:01.870 will look at it at one point. 03:01.870 --> 03:07.830 But but most of the time you're running the servers locally and with apologies for the repetition. 03:07.830 --> 03:11.690 But you know, sometimes it helps to repeat just just like him prompting. 03:11.890 --> 03:14.650 It helps to repeat that when you're explaining things as well. 03:14.890 --> 03:21.090 But with that, what we're doing today is mostly making an MCP server, and we'll also make an MCP client. 03:21.090 --> 03:24.210 But that's a little bit of a of a red herring, as I'll explain. 03:24.210 --> 03:27.010 But this is mostly what we're going to be doing making an MCP server. 03:27.010 --> 03:28.850 And the question is why does one do that? 03:28.890 --> 03:31.330 Why do you create an MCP server? 03:31.330 --> 03:34.090 And the main reason you do it is for sharing. 03:34.210 --> 03:39.490 You're doing it because you're going to publish your MCP server somewhere and allow other people to 03:39.530 --> 03:42.370 incorporate your tools and resources. 03:42.370 --> 03:43.370 And maybe prompts. 03:43.890 --> 03:48.930 Less seems less common, but your tools mostly are in their projects. 03:49.250 --> 03:50.450 That is the reason. 03:50.490 --> 03:52.810 The primary reason for making MCP server. 03:53.050 --> 03:57.930 Also, if in your project you're using a bunch of MCP servers yourself that you're sharing, maybe you'd 03:57.930 --> 04:04.050 like to be consistent in terms of how you arm your LM, so you'd like to have your own MCP server to 04:04.090 --> 04:05.770 combine it with all of the others. 04:06.170 --> 04:10.610 And it's also worth doing it as an exercise to understand what happens behind the scenes. 04:10.610 --> 04:16.740 Building our own will help to reveal the the bits and pieces that make up MCP servers. 04:17.380 --> 04:22.220 But there are some reasons not to make an MCP server, and there's really just one of them I wanted 04:22.220 --> 04:28.020 to highlight, which is that, I mean, look, if we're making this just for our own project, for our 04:28.020 --> 04:35.580 own purposes, so we've got some tools and we would like to use them with our LLM then remember, like, 04:35.620 --> 04:39.420 it's actually really easy these days just to make a function into a tool. 04:39.460 --> 04:43.860 Back in the day, you needed to have all of that stuff around turning that that JSON gumph. 04:44.060 --> 04:49.700 But these days, if you're using open AI agents SDK, you're just putting an app function tool decorator 04:49.700 --> 04:52.380 over your function and then it's becoming a function tool. 04:52.420 --> 04:53.340 It's a tool right away. 04:53.340 --> 04:56.420 You can just pass that in as a tool into the agent. 04:56.620 --> 04:58.860 So it is quite easy to do this. 04:58.900 --> 05:02.900 And this is certainly something that is worth keeping in mind. 05:03.420 --> 05:10.260 It's not particularly worth building an MCP server just if it's only for your own personal use internally. 05:10.500 --> 05:13.980 Uh, and you might as well just just use a function tool decorator. 05:13.980 --> 05:17.180 So keep that keep that context in mind as we launch into this.