WEBVTT 00:00.120 --> 00:05.600 And it's great to be back in cursor for this big moment of making our own MCP server. 00:05.920 --> 00:06.320 All right. 00:06.320 --> 00:09.200 We're going into folder six of course. 00:09.240 --> 00:11.760 And first of all, well let me just bring you to the lab. 00:11.760 --> 00:12.360 Here we go. 00:12.400 --> 00:17.760 So week two, day two about to create and use our own MCP server and client. 00:17.800 --> 00:21.520 I do want to make the point that whilst this is pretty simple to do, it's not like it's incredibly 00:21.520 --> 00:22.120 straightforward. 00:22.120 --> 00:23.920 There is going to be some stuff. 00:24.160 --> 00:29.720 And the important thing to do, it's less about the magic of MCP, is less about whether it's easy to 00:29.760 --> 00:31.000 make your own server. 00:31.000 --> 00:34.680 It's more about how easy it is to share and use other people's servers. 00:34.680 --> 00:37.280 So keep that in again, that context in mind. 00:37.600 --> 00:43.080 The first thing we're going to do is go and look at some code in a in a Python module called accounts. 00:44.440 --> 00:45.840 And this is a code. 00:46.200 --> 00:51.560 This is a module which allows you to manage transactions. 00:51.560 --> 00:57.400 It will keep track of transactions for different people who are buying and selling shares. 00:57.640 --> 01:00.320 Um it has it's it's got a class account. 01:00.480 --> 01:08.630 And that class account has a account name a balance Strategy holdings, a list of transactions, and 01:08.630 --> 01:11.910 a time series of the portfolio value. 01:12.430 --> 01:14.910 So there's quite a lot to this. 01:15.190 --> 01:18.390 Um, and it's an interesting piece of code. 01:18.390 --> 01:26.390 You can buy shares, you can sell shares, you can calculate the portfolio value and do some other things 01:26.390 --> 01:26.870 here. 01:27.150 --> 01:33.550 Um, so a nice little utility for managing, buying and selling shares and maintaining an account. 01:33.550 --> 01:35.550 And maybe you know where this is going. 01:35.590 --> 01:41.950 But if you could cast your mind back a couple of weeks, this of course, this is the code that was 01:41.950 --> 01:45.430 written by our engineering team of agents. 01:45.630 --> 01:51.470 This is one that that, uh, is the fine work of our back end developer, our engineering lead. 01:51.470 --> 01:54.230 And somewhere there's also a test class to test this as well. 01:54.230 --> 01:55.670 And it's being tested. 01:55.710 --> 01:57.910 Now, of course, I've added in a few details here and there. 01:57.910 --> 02:02.670 I actually put in that time series thing I added in the strategy of the portfolio. 02:02.670 --> 02:07.310 So a couple of things I've just gone through and added in and I did, I think I did find a small bug 02:07.310 --> 02:08.630 that I had to fix as well. 02:08.910 --> 02:16.870 But generally speaking, this code was written by our engineering team of agents in Crew Week. 02:17.150 --> 02:19.190 And so this this was the result of week three. 02:19.190 --> 02:23.790 And so if you skipped week three, then you missed out because this was really cool, really fun. 02:23.790 --> 02:28.110 And you could see how to build an engineering team that writes code like this, builds a whole module 02:28.110 --> 02:30.350 and tests it on your behalf. 02:30.950 --> 02:35.790 The other thing I've added at the very top of it is I just put in some SQL which which I hadn't asked 02:35.790 --> 02:42.070 for in the original requirements, so that an account can be written and read from a SQLite database. 02:42.070 --> 02:44.470 But this is just Python code. 02:44.510 --> 02:50.270 This has got nothing to do with MCP, but it's a little tool, a set of tools, some useful code that 02:50.270 --> 02:56.350 we have written or well, we haven't written that our engineering team has written, and we want to 02:56.390 --> 02:59.270 now turn this into an MCP server. 02:59.270 --> 03:05.750 So we want to build an MCP server that can expose this functionality as tools with descriptions. 03:05.750 --> 03:08.670 So imagine you just got this off the shelf from your team. 03:08.670 --> 03:11.230 It's time to turn this into an MCP server. 03:11.230 --> 03:13.860 So this module was called accounts dot Pi. 03:13.900 --> 03:18.420 And for the MCP server I'm going to take you to accounts underscore server dot pi. 03:18.620 --> 03:24.300 So again this is us building our own MCP server to use. 03:24.500 --> 03:27.820 Take advantage of this code in accounts dot pi. 03:27.980 --> 03:29.060 And here it is. 03:29.060 --> 03:33.500 It's it's very short and it's mostly natural language as you might expect. 03:33.500 --> 03:39.060 It's text and it's, it's wrapper code to wrap our Python code. 03:39.060 --> 03:42.540 But you could equally well just have the Python code right here like you don't. 03:42.580 --> 03:45.420 You don't need to do it the way I've done it, but I've I've kept them separate. 03:45.420 --> 03:53.140 So you can clearly delineate the business logic in accounts dot pi from the MCP server in this accounts 03:53.180 --> 03:54.380 server dot pi. 03:54.700 --> 03:59.660 So this from MCP server fast import fast MCP. 04:00.180 --> 04:02.380 This is an anthropic code. 04:02.380 --> 04:04.740 This is nothing to do with OpenAI agents SDK. 04:04.940 --> 04:11.260 This is MCP code a way to build your own quickly build your own MCP server. 04:11.620 --> 04:17.490 And we are then importing Business logic accounts. 04:18.130 --> 04:22.210 We're importing the class account that was set in in that package. 04:22.330 --> 04:25.210 And as I say equally, you could just write the code right here. 04:25.210 --> 04:27.570 But but we're separating out the logic. 04:27.930 --> 04:34.250 So here's an example of a tool that we want to make available through our MCP server. 04:34.250 --> 04:36.050 And it is pretty simple. 04:36.050 --> 04:37.530 There's very little to it. 04:37.530 --> 04:41.010 You put a decorator MCP tool like that. 04:41.290 --> 04:45.810 And then here we have our the function that is going to become our tool. 04:46.010 --> 04:47.210 It's async. 04:47.570 --> 04:51.210 We we give it an the function name of course. 04:51.530 --> 04:53.890 And then this is the one parameter. 04:54.130 --> 04:57.970 We have docstrings to say what it does. 04:58.170 --> 05:01.610 And we use docstrings to state the parameters. 05:01.930 --> 05:08.410 And then this is the logic which in our case is just delegating to our business logic to get the name 05:08.410 --> 05:09.770 and return the balance. 05:09.770 --> 05:13.370 So that will become a get balanced tool. 05:13.410 --> 05:18.810 Given a name, it will create a new account for, or it will access the account for that person and 05:18.810 --> 05:19.880 get their balance. 05:20.200 --> 05:21.120 That's the tool. 05:21.400 --> 05:22.120 This is it. 05:22.160 --> 05:22.960 With this, we have. 05:23.000 --> 05:25.360 We could have we could just stick with get balanced. 05:25.360 --> 05:26.880 And that could be our MCP server. 05:26.880 --> 05:30.320 We're going to add some more functions but that's all there is to it. 05:30.600 --> 05:35.640 So then we're going to have like Get Holdings which just does the same thing for Holdings by shares 05:35.640 --> 05:36.840 which does the same thing. 05:37.000 --> 05:37.960 Sell shares. 05:38.280 --> 05:41.800 And then we've got a resource at the end of it. 05:41.800 --> 05:47.440 So I as I explained MCP servers have tools, resources and prompts. 05:47.480 --> 05:51.240 We're not going to cover prompts because they're just not not that that great to use. 05:51.240 --> 05:53.360 But it's very similar concept to this. 05:53.360 --> 06:02.160 But we've shown tools and used sometimes as resources and with resources you have like a, like a URL 06:02.200 --> 06:06.320 kind of construct that describes the resource that will be asked for. 06:06.520 --> 06:10.120 And I'm suggesting it's, you know, there's some discretion as to how you do this. 06:10.160 --> 06:13.920 You sort of put here what kind of thing are you talking about? 06:13.960 --> 06:17.680 And then your MCP server and then any arguments. 06:17.760 --> 06:20.560 So in our case we've got a URL we've constructed here. 06:20.560 --> 06:25.360 If someone looks for accounts Account server and then passes in someone's name. 06:25.560 --> 06:29.240 It will look up their account and return a report of it. 06:29.720 --> 06:31.960 So that is it. 06:32.120 --> 06:41.160 And if this is run, then it just calls MCP and it selects the transport as standard input output. 06:41.200 --> 06:46.760 The basic, simple uh, type that you use for local MCP servers. 06:47.240 --> 06:48.880 And this this is it. 06:48.880 --> 06:50.680 This is building your MCP server. 06:51.000 --> 06:52.200 That's all there is. 06:52.200 --> 06:55.560 You could do this yourself with just one tool and just see it working. 06:55.800 --> 06:56.640 You can also see. 06:56.640 --> 06:57.840 I hope you understand what I mean. 06:57.840 --> 07:03.400 We could equally have just simply put these decorators directly into accounts dot pi. 07:03.440 --> 07:04.960 We didn't really need the separation. 07:04.960 --> 07:12.000 We could have just put the MCP decorators all the way through this and instantly exposed these functions. 07:12.240 --> 07:14.120 I just separated out because that's a bit cleaner. 07:14.120 --> 07:19.720 And that means that you can apply this to any of your own code to build an MCP server just like that. 07:20.160 --> 07:26.160 Okay, if it's really that easy, then we should be able to just use this in our in our notebook. 07:26.440 --> 07:27.360 Let's see if we can.