Is it safe to deploy without ssh-agent on GitHub Actions?

I see 2 options here, using ssh-agent:

name: deploy
on: [push]
jobs:
  deploy:
    runs-on: ubuntu-20.04
    env:
      USER_HOST: ec2-user@ec2...
      HOST_KEY: ec2... ecdsa-sha2-nistp256 AAAA...mXU=
    steps:
      - name: Check out the code
        uses: actions/checkout@v2

      - name: Run ssh-agent
        uses: webfactory/[email protected]
        with:
          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}

      - name: Add the host key to ~/.ssh/known_hosts
        run: |
          echo "$HOST_KEY" >> ~/.ssh/known_hosts

      - name: Deploy
        run: |
          set -x
          BRANCH=${GITHUB_REF#refs/heads/}
          cat .github/deploy.sh | ssh -T "$USER_HOST" sh -s "$BRANCH"

And w/o ssh-agent:

name: deploy
on: [push]
jobs:
  deploy:
    runs-on: ubuntu-20.04
    env:
      USER_HOST: ec2-user@ec2...
      HOST_KEY: ec2... ecdsa-sha2-nistp256 AAAA...mXU=
    steps:
      - name: Check out the code
        uses: actions/checkout@v2

      - name: Set up ssh
        run: |
          set -x
          mkdir ~/.ssh
          echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_rsa
          chmod 0600 ~/.ssh/id_rsa
          echo "$HOST_KEY" >> ~/.ssh/known_hosts
        env:
          SSH_PRIVATE_KEY: ${{ secrets.SSH_PRIVATE_KEY }}

      - name: Deploy
        run: |
          set -x
          BRANCH=${GITHUB_REF#refs/heads/}
          cat .github/deploy.sh | ssh -Ti ~/.ssh/id_rsa "$USER_HOST" sh -s "$BRANCH"

Are both of them safe? Or should one of them be preferred? webfactory/ssh-agent doesn't store the key on disk.