AI tool comparison
Craft Agents vs Terrarium
Which one should you ship with? Here is the side-by-side panel verdict, pricing read, reviewer split, and community vote comparison.
Developer Tools
Craft Agents
Open-source desktop app for multi-session Claude agents with MCP & APIs
75%
Panel ship
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Community
Free
Entry
Craft Agents OSS is an open-source desktop application built on Anthropic's Claude Agent SDK, offering a polished GUI for managing multiple AI agent sessions simultaneously. Built by Luki Labs and released under Apache 2.0, it fills the gap between raw API access and the full Claude.ai web interface — giving developers and power users a native desktop experience with serious capability depth. The app supports three permission modes that make it genuinely useful for real work: Explore (read-only, safe for exploring codebases), Ask to Edit (approval-based, for supervised automation), and Auto (unrestricted, for trusted workflows). It connects to MCP servers, REST APIs from Google, Slack, and Microsoft, and local filesystems, with real-time streaming responses and full tool call visualization. A multi-session workflow with Todo → In Progress → Needs Review → Done status tracking makes it feel more like a project management system than a chat interface. Built on Electron + React with encrypted credential storage and a headless server mode, Craft Agents is architecturally serious. It's available as a one-line installer for macOS, Linux, and Windows. With the Claude Agent SDK gaining traction, this is the first polished desktop client that treats agents as long-running workflows rather than single-turn conversations.
Developer Tools
Terrarium
Evals that actually simulate real deployment — stateful, multi-turn, alive
50%
Panel ship
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Community
Paid
Entry
Terrarium is a multi-turn evaluation and optimization engine for LLM agents built by evolvent-ai. Unlike static benchmark suites that measure agents against fixed input-output pairs, Terrarium creates persistent, stateful "living environments" — simulated deployment contexts where agents operate over extended sessions, accumulate state, use tools, and interact with simulated external systems. You evaluate agents the way you'd test a car: by driving it, not by measuring its doors. The system supports configurable environment complexity, including simulated databases, APIs, file systems, and user personas. Agents are scored not just on final outputs but on trajectory quality — how efficiently they reached the answer, how often they hallucinated intermediate steps, and how well they recovered from dead ends. The engine also supports continuous optimization loops where poor-performing trajectories trigger automatic prompt refinement. With 17 stars and created April 14, Terrarium is extremely new. But it's addressing a genuine gap: the disconnect between how agents perform on static benchmarks versus how they behave in production. As enterprise AI deployments scale, the need for realistic pre-production evaluation is becoming critical.
Reviewer scorecard
“The three permission modes — Explore, Ask to Edit, Auto — is the right model for how I actually use agents. I want read-only exploration when I'm learning a codebase and auto mode when I'm in flow. That plus MCP server support makes this my new default agent UI.”
“Static evals are lying to us constantly — agents that ace benchmarks fall apart in production because benchmarks don't have state, side effects, or accumulated context. Terrarium's living environments model is the right approach to catching real failure modes before deployment.”
“Electron desktop apps for AI agents have a graveyard of predecessors — most people end up in the terminal or the browser anyway. The Claude-only model dependency is also a real limitation; when Anthropic changes their SDK or pricing, the whole platform needs to adapt.”
“Building a realistic simulation of your production environment is often harder than just running the agent in staging. The value proposition assumes your eval environment is meaningfully closer to production than your existing test suite — which is a big assumption for complex deployments.”
“Agent session management as a first-class concept is where the whole category is heading. Craft Agents is early proof that the IDE model — multi-session, persistent, project-aware — is the right UX paradigm for AI agents, not the chat-box model we inherited from GPT-3 days.”
“The eval-optimize loop is the missing piece in most AI agent development workflows. Tools that can automatically identify weak trajectories and suggest improvements will become as fundamental as unit tests. Terrarium is early, but the category is inevitable.”
“File attachments with automatic format conversion plus the Slack/Google API integrations mean I can finally have agents that work across my whole toolkit, not just the terminal. The one-line installer is the detail that will make this actually get adopted.”
“This is deeply technical infrastructure that won't affect my daily workflow. The people who need this know they need it — but for most creators building with AI tools, static evals are already more than they use.”
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