Argus

An MCP server that tests apps like a real testing engineer—exploring user journeys, discovering unscripted bugs, and proving each finding before reporting it.

Argus is an MCP server. It adds evidence-first browser QA to Claude Code, Codex, Cursor, or any MCP host without taking over the host agent's identity or broader coding task. The agent explores, inspects, verifies persistence, and records reproducible bugs. Every certified finding is independently re-confirmed from a clean page load before it's reported.

Product page · Quick start · Why Argus · Compared · Tools · Benchmarks

The output

Give it a URL; get a report of bugs — each tagged with whether Argus independently reproduced it or only observed it:

The green badge is the whole point. Anyone can have an LLM claim a bug. Argus re-loads the page from scratch and re-checks the symptom before it says VERIFIED — so the report is a list of bugs you can trust, not a list of guesses to triage.

How it works

flowchart LR
    A(["observe"]) --> B{"looks wrong?"}
    B -->|not sure| C["act: click · type · resize · verify"]
    C --> A
    B -->|bug| D["verify_persistence — reload from a clean state"]
    D -->|symptom repeats| E(["VERIFIED"])
    D -->|symptom gone| F(["dropped — no false positive"])
    E --> G[["report: HTML · JSON · JUnit · SARIF"]]

The agent is the intelligence. Argus supplies concise QA guidance, a description-keyed tool surface (click_what("Login button"), not click(7)), a goal coverage ledger, and a reproduction-receipt engine that turns "the model thinks this is a bug" into "this bug is real, here's the proof."

Quick start

With uv installed, no global Python package install is required. Install Chromium once:

uvx --from playwright playwright install chromium

Then connect Argus to your MCP client.

Claude Code

claude mcp add argus -- uvx --from argus-testing argus-mcp

Codex and the ChatGPT desktop app

Codex CLI, the Codex IDE extension, and the ChatGPT desktop app share the same local MCP configuration:

codex mcp add argus -- uvx --from argus-testing argus-mcp

Cursor

The button adds Argus to Cursor; run the Chromium installation command above once before the first test.

Any stdio MCP client

{
  "mcpServers": {
    "argus": {
      "command": "uvx",
      "args": ["--from", "argus-testing", "argus-mcp"]
    }
  }
}

The default core profile exposes the primary web-testing workflow without flooding the host with every specialist tool. Use uvx --from argus-testing argus-mcp --list-tools to inspect the selected profile, --tool-profile screen for native macOS testing, or --tool-profile full for the entire advanced surface. ARGUS_TOOL_PROFILE provides the same setting through the environment.

Then just ask, in your agent session:

"Test my app at http://localhost:3000 — find real bugs."

That's it. The agent drives; Argus keeps it honest and writes the report.

For a scoped review, the host can give start_session explicit goals, constraints, and an advisory time_budget_minutes. Argus returns the full testing protocol once and keeps outstanding goals and discovered pages visible in later observations. Mark a goal in_progress before its journey; when coverage_update marks it exercised or blocked, Argus requires a concrete explanation and automatically links the URLs, value-redacted actions, screenshots, persistence checks, bugs, and observations produced in that testing window. The final HTML and JSON reports preserve both completed and unfinished coverage instead of implying that an incomplete pass was comprehensive.

pip install argus-testing
playwright install chromium
claude mcp add argus -- argus-mcp

# Uses a LiteLLM-backed planner. Set a provider key (OPENAI_API_KEY, DEEPSEEK_API_KEY, …).
uvx --from argus-testing argus http://localhost:3000 --model deepseek/deepseek-chat

# Higher recall: union N independent passes (deduped, proven instance kept)
uvx --from argus-testing argus http://localhost:3000 --passes 3

pip install 'argus-testing[mac]'
brew install cliclick          # keystroke / coordinate fallback
argus-mcp --doctor             # check Screen Recording + Accessibility grants
claude mcp add argus-screen -- argus-mcp --tool-profile screen

Artifact and resource limits

Argus writes each run's screenshots into its own run directory so later tests cannot overwrite earlier evidence. Long browser sessions also keep bounded in-memory event logs and only read response bodies for inspectable API traffic; binary and oversized bodies are skipped before they enter Python memory.

Report cleanup is explicit and dry-run by default. The newest 20 complete runs are protected in this example; .argus journals and state capsules are never deleted:

argus-cleanup --output ./argus-reports --keep-runs 20
argus-cleanup --output ./argus-reports --keep-runs 20 --apply

Use --older-than-days and --max-size-mb for stricter policies. Advanced limits can be adjusted with ARGUS_MAX_NETWORK_EVENTS, ARGUS_MAX_ERROR_EVENTS, ARGUS_MAX_DOWNLOAD_EVENTS, ARGUS_MAX_DIALOG_EVENTS, ARGUS_MAX_RESPONSE_BODY_BYTES, and ARGUS_MAX_RESPONSE_READ_BYTES. Responses without a declared length are skipped by default; ARGUS_CAPTURE_UNKNOWN_LENGTH_BODY=1 opts into reading them. When a limit discards old evidence, Argus says so in tool output and the final session summary.

Why Argus is different

Existing testing tools only test what you script. Playwright and Cypress run the assertions you wrote. Argus discovers bugs you didn't think to test for — and then does the thing an LLM alone can't be trusted to do: proves them.

How it compares

On the axis that matters for finding bugs — autonomously discover, independently verify, and report — Argus occupies a different slot from the browser-MCP crowd:

These aren't "worse" tools — they're a different job. Playwright MCP gives an agent excellent hands; Chrome DevTools MCP gives it deep network/perf/memory inspection Argus doesn't have. Argus is the layer that decides what's a bug and proves it. Use them together.

Benchmarks

$ python -m argus.bench --target all