The speaker is inside, at home, surrounded by "good words," which could mean books, or perhaps the words of their own writing. Either way, it's a comfortable, protected place. The title, "Agoraphobic," tells us why the speaker stays there: a fear of open or public spaces. So the cozy scene carries a quiet tension. The home is a refuge, but it may also be a limit.
Then the poem turns outward. Spring is "beginning now / to be dirty." That's an unexpected way to describe the season. Instead of fresh flowers, we get mud, wet ground, things stirring and breaking open. Spring is lively and untidy, and it's happening out there, beyond the speaker's reach. The speaker watches it, or senses it, from a distance.
The mood is calm but a little wistful. There's no panic, just a gentle awareness of what the speaker is choosing, or perhaps unable, to join. The short lines and sparse words make the poem feel quiet and still, like the room itself.