Call a Tool on an MCP Server

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Demonstrates Mcp.CallTool, which calls the MCP tools/call method for a named tool, passing a JSON arguments object and receiving the tool's result. The example calls the Microsoft Learn microsoft_docs_search tool.

Tip: Code to parse the returned JSON can be generated with Chilkat's online tool at https://tools.chilkat.io/jsonParse.

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    const mcp = try chilkat.Mcp.init();
    defer mcp.deinit();

    // Connect to a public MCP (Model Context Protocol) server over its Streamable HTTP endpoint.  The
    // Microsoft Learn MCP server is public and requires no authentication.
    mcp.connect("https://learn.microsoft.com/api/mcp") catch {
        std.debug.print("{s}\n", .{try mcp.getLastErrorText(alloc)});
        return;
    };

    // Build the tool's input arguments.  The members required depend on the tool's input schema (see
    // ListTools).  Here the Microsoft Learn "microsoft_docs_search" tool takes a search query.
    const args = try chilkat.JsonObject.init();
    defer args.deinit();
    args.updateString("query", "How do I create an Azure storage account?") catch {};

    // Call the MCP tools/call method for the named tool.  The tool's result is placed in the result
    // JsonObject.
    const result = try chilkat.JsonObject.init();
    defer result.deinit();
    mcp.callTool("microsoft_docs_search", args, result) catch {
        std.debug.print("{s}\n", .{try mcp.getLastErrorText(alloc)});
        return;
    };

    result.setEmitCompact(false);
    std.debug.print("{s}\n", .{try result.emit(alloc)});
    // JSON parsing code for this result can be generated at Chilkat's online tool:
    // https://tools.chilkat.io/jsonParse
}