Playwright MCP

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already provide readOnlyHint=true, destructiveHint=false, and openWorldHint=true, indicating this is a safe, non-destructive operation that can open any URL. The description adds context by specifying it opens 'a new tab' (not just any browser action), which complements the annotations without contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, efficient sentence that states the core functionality without any wasted words. It's front-loaded with the essential action and resource, making it immediately clear what the tool does.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple tool with one optional parameter, good annotations, and no output schema, the description is minimally adequate. However, it lacks context about browser state requirements, what happens if no URL is provided (though the schema covers this), and how it relates to sibling tab management tools.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage, with the 'url' parameter fully documented in the schema itself. The description doesn't add any parameter information beyond what's in the schema, so it meets the baseline of 3 when schema coverage is high.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Open') and resource ('a new tab'), making the purpose immediately understandable. It doesn't explicitly differentiate from sibling tools like 'browser_tab_list' or 'browser_tab_select', but the verb 'Open' distinguishes it from those listing/selection operations.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'browser_navigate' (which might navigate in current tab) or 'browser_tab_list' (which lists tabs), nor does it specify prerequisites like needing an active browser session.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.