# Reticle

Verifies running web applications from the inside via MCP tools. The agent navigates, triggers actions, and asserts DOM states without screenshots.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 1269
- Author: reticlehq
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/reticlehq/reticle/tree/HEAD/server
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/reticle

## What it does

Reticle connects a coding agent directly to a live web application. The bridge hosts a local WebSocket endpoint at `ws://localhost:4400`, which links to the project's `@reticlehq/browser` SDK. Instead of relying on image recognition, the agent examines DOM state, inputs text, and observes reactions internally.

By default, the server exposes 10 tools, including `reticle_navigate`, `reticle_look`, `reticle_act`, `reticle_observe`, and `reticle_assert`. Only `reticle_act_and_wait` and `reticle_assert` return pass-fail verdicts; other tools move or inspect the page. Additional features like network mocking, clock control, and visual diffs stay hidden to keep token usage low. You run them via `reticle_run` or expose everything at once by setting `RETICLE_ADVERTISE_ALL_TOOLS=1`, which roughly doubles tool payloads.

The server requires the companion `@reticlehq/browser` SDK wired into the target application, which you configure via `npx @reticlehq/server init`.

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add reticle -- npx -y @reticlehq/server
```

### Codex

**Platform CLI**
```bash
codex mcp add server -- npx -y @reticlehq/server
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "server": {
            "command": "npx",
            "args": [
                "-y",
                "@reticlehq/server"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "server": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@reticlehq/server"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add server npx -y @reticlehq/server
```

## When to use it
- test running web apps directly from the inside without screenshots
- execute user interactions like clicks and form inputs via MCP tools
- validate DOM state with explicit verdict returns
- control browser clocks and mock network calls during agent runs

## Example prompts
- Navigate to the settings page and verify the save button using `reticle_assert`
- Click the submit button and wait for the response using `reticle_act_and_wait`
- Check what extra tools are available by running `reticle_tools`

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md