func CreateBranch()

in pkg/github/repositories.go [678:764]
74 lines of code
11 McCabe index (conditional complexity)

func CreateBranch(getClient GetClientFn, t translations.TranslationHelperFunc) (tool mcp.Tool, handler server.ToolHandlerFunc) {
	return mcp.NewTool("create_branch",
			mcp.WithDescription(t("TOOL_CREATE_BRANCH_DESCRIPTION", "Create a new branch in a GitHub repository")),
			mcp.WithToolAnnotation(mcp.ToolAnnotation{
				Title:        t("TOOL_CREATE_BRANCH_USER_TITLE", "Create branch"),
				ReadOnlyHint: false,
			}),
			mcp.WithString("owner",
				mcp.Required(),
				mcp.Description("Repository owner"),
			),
			mcp.WithString("repo",
				mcp.Required(),
				mcp.Description("Repository name"),
			),
			mcp.WithString("branch",
				mcp.Required(),
				mcp.Description("Name for new branch"),
			),
			mcp.WithString("from_branch",
				mcp.Description("Source branch (defaults to repo default)"),
			),
		),
		func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
			owner, err := requiredParam[string](request, "owner")
			if err != nil {
				return mcp.NewToolResultError(err.Error()), nil
			}
			repo, err := requiredParam[string](request, "repo")
			if err != nil {
				return mcp.NewToolResultError(err.Error()), nil
			}
			branch, err := requiredParam[string](request, "branch")
			if err != nil {
				return mcp.NewToolResultError(err.Error()), nil
			}
			fromBranch, err := OptionalParam[string](request, "from_branch")
			if err != nil {
				return mcp.NewToolResultError(err.Error()), nil
			}

			client, err := getClient(ctx)
			if err != nil {
				return nil, fmt.Errorf("failed to get GitHub client: %w", err)
			}

			// Get the source branch SHA
			var ref *github.Reference

			if fromBranch == "" {
				// Get default branch if from_branch not specified
				repository, resp, err := client.Repositories.Get(ctx, owner, repo)
				if err != nil {
					return nil, fmt.Errorf("failed to get repository: %w", err)
				}
				defer resp.Body.Close()

				fromBranch = *repository.DefaultBranch
			}

			// Get SHA of source branch
			ref, resp, err := client.Git.GetRef(ctx, owner, repo, "refs/heads/"+fromBranch)
			if err != nil {
				return nil, fmt.Errorf("failed to get reference: %w", err)
			}
			defer resp.Body.Close()

			// Create new branch
			newRef := &github.Reference{
				Ref:    github.Ptr("refs/heads/" + branch),
				Object: &github.GitObject{SHA: ref.Object.SHA},
			}

			createdRef, resp, err := client.Git.CreateRef(ctx, owner, repo, newRef)
			if err != nil {
				return nil, fmt.Errorf("failed to create branch: %w", err)
			}
			defer resp.Body.Close()

			r, err := json.Marshal(createdRef)
			if err != nil {
				return nil, fmt.Errorf("failed to marshal response: %w", err)
			}

			return mcp.NewToolResultText(string(r)), nil
		}
}