Playwright Tools for MCP

Here's a breakdown of the key themes in the Hacker News discussion, with supporting quotes:

The Promise and Practicality of LLMs Controlling Browsers with Playwright/MCP

The core excitement revolves around using LLMs, specifically with Playwright (or similar tools), to automate browser interactions, essentially giving the LLM a "pair of eyes and hands" on the web. This leads to interesting possibilities, like automated testing and bug fixing.

• "This is so good. I've been using it with Claude Code with great success... It's like working with a really great mid-level engineer. What a time to be alive." - mgdev expressing enthusiasm.
• "I’m going to see if I can use this in combination with our JIRA MCP to read a bug ticket’s “steps to reproduce” to see if it translate those steps to actually reproduce those actions...This is going to be the “App Store” for models in a way that OpenAI’s custom GPTs never was." - atonse, highlighting potential use cases and the "App Store" vision.

Cost Concerns and Token Usage

A major sticking point is the high cost associated with using LLMs, especially for tasks involving extensive context or complex interactions. Several users reported significant expenses when using Claude Code with Playwright.

• "Unfortunately, it's also very expensive. How do interactions with MCP servers affect token usage/cost?" - maleldil, directly questioning the economic viability.
• "I've spent $500 this week, $.10 - $1 at a time, fixing bugs and adding features" - drewnick, citing a personal costly experience.
• "I burned though $25 in just 3 hours. Claude code will be great when they can get the cost down. If the cost is like 1/10th of that I’d be using it all the time, but +/- $10 / hour is too much." - Aeolun stating a desire for cost reduction.

MCP (Model Control Protocol) and Its Significance

The term "MCP" appears frequently, referring to a protocol or architecture that allows LLMs to interact with external tools and environments. The discussion highlights the emerging ecosystem around MCPs and their potential to extend LLM capabilities.

• "I don’t understand the hate against MCP. It is truly exciting to see the Cambrian explosion of “connectors” coming out." - atonse, indicating a positive outlook on MCP's growing ecosystem.
• "Watermarking and synthesizing text for hosts and clients, private RAG over Slack MCP implementations would disperse LLM's to Local Data Souce: A, B, and remote server C." - mazacx5volvo240, using MCPs for local data access by LLMs.
• "I agree -- I hacked up a CDP-driven MCP so that Claude can drive your own browser instance, and I think that's more in the spirit of how MCP is supposed to work (where it's driving your tools under supervision, rather than spinning up its own context)" - dannyobrien, suggesting a vision for MCP where models supervise tools.

Playwright vs. Puppeteer and Browser Compatibility

The discussion touches upon the relative merits of Playwright compared to Puppeteer, another browser automation tool. Playwright is seen as an evolution, offering improvements in API design and broader browser support.

• "Playwright is a bit of an evolution of Puppeteer. Mostly the same API, extends the API a bit (I tend to prefer its abstractions over Puppeteer), and designed to work with multiple browsers. It came from many of the same developers as Puppeteer." - bdcravens, clearly differentiating the two tools.
• "I've been using Playwright for years testing safari/FF/chromium-based engines. Playwright team compiles every single browser at each new release." - epolanski, speaking to Playwright browser compatibility.

Challenges with Context and Alternative Approaches

Several users pointed out that naively feeding the entire DOM to the LLM can quickly exhaust the model's context window, leading to failures. They discussed alternative approaches for representing web page content in a more compact and efficient manner.

• "However, even with that, it will quickly exhaust the model context if you navigate to something like Gmail. I just verified this with cursor." - lxe, describing context limitations.
• lxe then provides a link to an alternative representation: "https://github.com/lxe/chrome-mcp/blob/master/src/runtime-te... This uses your own chrome session and doesn't require a huge context size."
• "pal9000i" is "wondering why they didn't just support the original Playwright APIs instead of the subset of actions." This implies simplification for the models is still an open problem.

Specific Use Cases and Future Applications

Beyond general enthusiasm, several users mentioned concrete use cases they were exploring, such as automated testing for Rails applications or replicating bug reports from JIRA.

• "I want an MCP for capybara so LLMs can write my Rails system tests and debug them when they don't work." - adamtaylor_13, desiring automated Rails system tests.
• "I’m going to see if I can use this in combination with our JIRA MCP to read a bug ticket’s “steps to reproduce” to see if it translate those steps to actually reproduce those actions." - atonse, specifying JIRA integration.

In summary, the discussion reflects excitement about the potential of LLMs to control web browsers and automate tasks, tempered by concerns about cost, token usage, and context limitations. The emergence of MCPs and the ongoing development of tools like Playwright are seen as key enablers for this new wave of automation.