Cursor Composer 2.5 is the third-generation in-house coding model from Cursor, released on May 18, 2026. It scored 62 on the Artificial Analysis Coding Agent Index, a 14-point jump over Composer 2, and it does so at roughly 10 to 60 times lower cost per task than Claude Opus 4.7 or GPT-5.5. The release puts Cursor in the same conversation as Anthropic and OpenAI on coding-model quality, while keeping it cheap enough to use as the default for everyday work. The question this guide answers: how do you turn what Composer 2.5 writes into a production app with auth, a database, and a custom domain?
Quick Answer
- Cursor Composer 2.5 is Cursor's own coding model, released May 18, 2026. It scored 62 on the Artificial Analysis Coding Agent Index, placing third behind Claude Opus 4.7 (66) and GPT-5.5 in Codex (65).
- It costs about $0.07 per task on the standard tier and $0.44 per task on Fast, roughly 10 to 60 times cheaper than the higher-effort variants of Opus and GPT-5.5 that beat it on quality.
- Composer 2.5 is excellent at multi-file edits inside a single repo. It does not deploy your app, run your database, handle auth, or attach a domain.
- Totalum is the natural production layer behind Composer 2.5. You edit code in Cursor, then call Totalum over MCP to deploy, persist data, and host on a custom domain.
- The chain takes about four lines of mcpServers config and works the same way for solo devs, agencies running client work, and SaaS teams shipping internal tools.
What is Cursor Composer 2.5?
Cursor Composer 2.5 is a mixture-of-experts language model that Cursor trains specifically for agentic coding. It is the direct successor to Composer 2 (released March 19, 2026) and Composer 1 (October 29, 2025). The 2.5 release lands four key improvements over Composer 2:
- Plus 14 points on the Artificial Analysis Coding Agent Index. Composer 2 scored 48. Composer 2.5 scored 62. That is the same band where Claude Opus 4.7 (66) and GPT-5.5 in Codex (65) sit, with Composer 2.5 in third place overall.
- Targeted reinforcement learning with textual feedback. Cursor trained the model on tasks where a coding agent walks through a goal and gets natural-language feedback at each step, not just pass-fail rewards.
- More synthetic data. Cursor expanded the synthetic corpus used to teach the model how to use coding tools, edit files, and ground reasoning in compiled output.
- Cost. Composer 2.5 standard runs about $0.07 per task and Composer 2.5 Fast runs about $0.44 per task in independent benchmarks. The medium-effort peers above it on the index cost $1.24 to $2.21 per task; the top two (Opus 4.7 max and GPT-5.5 xhigh) cost $4.10 and $4.82.
Composer 2.5 is positioned as Cursor's default agentic model. If you open the Composer panel in Cursor 3.4 or later and do not explicitly pick another model, you get Composer 2.5.
What changed in the May 18, 2026 release
The May 18 release was not just a quality bump. It changed three things that matter when you build full apps with Cursor:
- The default agentic model is now in-house. Earlier this year the default behind Composer was Claude Sonnet or GPT-4.1, depending on settings. With 2.5 ranked third on a public benchmark, Cursor's pricing math now favors running their own model for most tasks.
- The cost curve flipped. A typical Composer 2.5 standard task is roughly $0.07. That makes it cheaper than every other coding agent scoring above 60 on the Artificial Analysis index. Teams that capped Composer usage to control bills can lift those caps.
- The base model is Kimi-derived. Cursor has acknowledged the Kimi base publicly. External speculation suggests a future Composer 3 may move to a Grok-based or xAI-trained foundation. For now, the model behind Composer 2.5 is independent of Anthropic and OpenAI, which matters for teams worried about lock-in to a single foundation-model vendor.
Where Cursor Composer 2.5 ends and Totalum begins
Composer 2.5 is a coding model wrapped in an agent loop. It reads files, edits files, runs commands, and converges on a passing change. That is where it stops. To go from a passing change to a live application on the public internet, three things still need to happen:
- Building. The repo Composer just edited needs to compile and bundle into a deployable artifact.
- Shipping. That artifact needs to land on hosting that serves real traffic, with a custom domain, TLS, and edge caching.
- State. Most real apps need a database, an auth system, file storage, a payment processor, and email. Composer can write code that calls these systems but cannot host them.
Totalum is the part of the stack that closes those three gaps. It is a Vibe Coding as a Service platform that takes a Next.js project (the same shape Cursor edits) and gives it auth, a hosted database, file storage, payments, email, AI integrations, and deployment to a custom domain. It exposes itself as an MCP server, so Composer 2.5 inside Cursor can call Totalum directly to create the project, push code, deploy, and read or write database rows.
The handoff is the cleanest production pattern we have seen for Cursor users in 2026. Composer 2.5 does the thinking. Totalum does the shipping. The boundary is the mcpServers configuration block in your Cursor settings, which we show below.
Composer 2.5 vs Composer 2 vs Claude Code vs Codex
| Feature | Composer 2.5 | Composer 2 | Claude Code (Opus 4.7) | Codex CLI (GPT-5.5) |
|---|---|---|---|---|
| Released | May 18, 2026 | Mar 19, 2026 | Apr 2026 (Opus 4.7) | May 2026 |
| Artificial Analysis index | 62 (3rd) | 48 | 66 (1st) | 65 (2nd) |
| Standard cost per task | $0.07 | $0.10 to $0.15 | $4.10 (max) | $4.82 (xhigh) |
| Fast / lower-latency tier | $0.44 per task | $0.30 per task | n/a | n/a |
| Where it runs | Cursor app and Cursor CLI | Cursor app and Cursor CLI | Claude Code CLI, Claude.ai | OpenAI CLI, ChatGPT |
| Multi-file edits in one repo | Yes (native) | Yes | Yes | Yes |
| MCP support | Yes | Yes | Yes | Yes |
| Built-in deploy step | No | No | No | No |
| Best for | Day-to-day agentic coding at low cost | Same, older generation | Hardest reasoning tasks | Long-context refactors |
The verdict here is narrow. Composer 2.5 is the best price-quality default in May 2026 for everyday coding work. Claude Opus 4.7 and GPT-5.5 still win on the hardest tasks, at roughly 10 to 60 times the cost. None of them deploy your app. That is the gap Totalum fills.
If you want a deeper head-to-head on the other two, see our Claude Code vs Codex CLI comparison and the best AI coding agents in 2026 pillar guide.
Tutorial: ship a Cursor Composer 2.5 build to production with Totalum
The full chain takes about ten minutes the first time. After that, every change you ask Composer to make can land on production from inside Cursor.
Step 1: install the Totalum MCP server
In your Cursor settings file (~/.cursor/mcp.json or the project-level .cursor/mcp.json), add Totalum as an MCP server:
{
"mcpServers": {
"totalum": {
"command": "npx",
"args": ["-y", "@totalum/mcp"],
"env": {
"TOTALUM_API_KEY": "your-totalum-api-key"
}
}
}
}Get the API key from your Totalum account page. Restart Cursor so the MCP server is picked up.
Step 2: create a Totalum project from Composer
Open the Composer panel in Cursor, confirm Composer 2.5 is selected, and ask it to create a Totalum project. Composer will call the totalum.createProject tool through the MCP server you just registered.
Create a new Totalum project called "lead-tracker" with a Next.js template, then add a leads table with fields: name (string), email (string), status (options: new, contacted, won, lost).Composer will issue two MCP calls: one to create the project, one to create the table. The project ships with auth, file storage, and Stripe wired in by default.
Step 3: edit the code locally
Pull the generated Next.js codebase to your machine. Open it in Cursor as a new workspace. From here, ask Composer to build the actual UI:
Build a /leads page that lists every row in the leads table, with a form to add a new lead. Use the existing api.post helper from src/lib/api.ts.Composer 2.5 reads the Totalum-generated codebase, edits the right files, and converges on a passing change.
Step 4: deploy through MCP
When the change is ready, ask Composer to deploy:
Deploy the current branch to the Totalum project lead-tracker. Wait for the deploy to complete and report the live URL.Composer calls totalum.deploy through MCP. Totalum builds the project on Cloudflare and returns the live URL. There is no separate CI step, no manual git push, no Vercel dashboard to open.
Step 5: connect a custom domain (optional)
Add the domain leads.acme.com to the lead-tracker project. Use the addCustomDomain tool.Totalum returns the DNS records you need to add. Once they propagate, the site is live on the custom domain with TLS.
The same five steps run identically for solo devs, agencies who manage many client projects in parallel, and SaaS teams who use Totalum as the backend builder behind a customer-facing product. For the agent-side patterns specifically, see our Claude Code MCP tutorial, which uses the same MCP server from the Claude side.
When to use Composer 2.5 alone, and when to bring Totalum into the chain
Composer 2.5 alone is enough when:
- You are editing an existing codebase that already has its own hosting and database.
- You are prototyping locally and do not need to share the result on the public internet.
- You are writing scripts, ETL jobs, or CLI tools that run on your machine.
Composer 2.5 plus Totalum is the right chain when:
- You need the output to be a deployed web app with auth, a database, and a custom domain.
- You want code ownership (the project lives in your account and you can export it as a Next.js repo).
- You want one MCP integration that handles deploy, database, storage, payments, and email, instead of stitching them together yourself.
- You are running multiple client projects in parallel and want each one isolated.
If you already evaluated Cursor's cloud agents pattern, the local Composer 2.5 plus Totalum chain is the same shape but runs on your machine instead of Cursor's cloud. Use cloud agents when you want fleets of long-running jobs. Use local Composer 2.5 plus Totalum when you want a tight feedback loop.
How Cursor Composer 2.5 compares to the other big coding-agent stories of May 2026
Three things shipped within a week of each other:
- Cursor Composer 2.5 (May 18, 2026): third on the Artificial Analysis benchmark, cheapest model above score 60.
- Claude Code Skills (Anthropic, ongoing roll-out): packaged Skills that ship as a SKILL.md plus tool calls, growing 904,900 percent year over year on search demand.
- Vercel x Claude Managed Agents (May 18, 2026): Anthropic Managed Agents now runnable on Vercel Sandbox.
The pattern across all three is that the coding agent itself is becoming a commodity. What separates one workflow from another is everything that happens AFTER the agent is done editing: where the code runs, how state is persisted, how you ship a change to production. That is the surface Totalum optimizes. See our pillar guide on the best AI coding agents in 2026 for a fuller cross-comparison across Cursor, Claude Code, Codex, Cline, and the rest.
If you are evaluating Cursor specifically against Claude Code today, our Cursor vs Claude Code in 2026 head-to-head walks the model and tooling differences side by side. If you are on Windows and stuck choosing a coding agent, our Codex on Windows with Totalum guide covers the parallel pattern for the OpenAI side.
FAQ
What is Cursor Composer 2.5?
Cursor Composer 2.5 is the in-house coding model that Cursor released on May 18, 2026. It is a mixture-of-experts model trained for agentic coding (multi-file edits, tool use, iterative reasoning), and it scored 62 on the Artificial Analysis Coding Agent Index, placing third behind Claude Opus 4.7 max and GPT-5.5 xhigh.
Is Composer 2.5 free in Cursor?
Composer 2.5 is included in Cursor's standard pricing plans. The Pro plan ($20 per month) includes $20 worth of Composer and Auto usage at the standard task rate ($0.07 per task), which works out to a generous monthly cap for most solo developers. Heavier usage is billed at the published per-task rate.
What model does Cursor Composer use?
Composer 2.5 is built on a Kimi base, fine-tuned by Cursor with reinforcement learning and synthetic data on agentic coding tasks. Cursor has acknowledged the Kimi foundation publicly. Composer 1 and Composer 2 used the same family. Future versions may move to a different base; for now, Composer 2.5 is the production model.
How do I open the Composer in Cursor?
In Cursor 3.4 or later, press Cmd plus I on Mac (or Ctrl plus I on Windows and Linux) to open Composer. The default model is Composer 2.5 unless you have changed it in settings. You can also pick a different model from the dropdown at the bottom of the Composer panel.
Composer 2.5 vs Claude Opus 4.7, which is better?
Claude Opus 4.7 (max effort) scored 66 on the Artificial Analysis Coding Agent Index, four points above Composer 2.5. It is the better choice for the hardest reasoning tasks. The tradeoff is cost: Opus 4.7 max costs about $4.10 per task, roughly 60 times the $0.07 cost of Composer 2.5 standard. For everyday agentic coding, Composer 2.5 wins on price-quality. For the toughest debugging or architectural work, Opus 4.7 still has the edge.
How does Cursor Composer 2.5 deploy to production?
Composer 2.5 does not deploy your app on its own. It edits the code and converges on a passing change inside Cursor. To deploy, you need a hosting layer. The cleanest pattern is to add Totalum as an MCP server in your Cursor settings, then ask Composer to call the totalum.deploy tool when a change is ready. Totalum builds on Cloudflare and returns a live URL, with auth, database, and custom domain support included.
Can I use Composer 2.5 with an existing Next.js project?
Yes. Composer 2.5 reads any codebase you open in Cursor. If you want production hosting, database, auth, and a custom domain for that existing project without rewriting it, you can import the project into Totalum as a Next.js template. Composer can then drive both the local edits and the deploy step from one MCP integration.
Ready to build with Totalum?
Cursor Composer 2.5 just lowered the cost of agentic coding by an order of magnitude. The bottleneck for shipping real apps moved from "is the model good enough" to "where does the code actually run." Totalum gives you the production layer in one MCP integration: auth, database, file storage, payments, email, AI integrations, and deployment to a custom domain.