Playwright MCP Server

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

Annotations indicate destructiveHint=true and readOnlyHint=false, which the description doesn't contradict (it implies a write action by 'press'). However, the description adds minimal behavioral context beyond annotations—it doesn't explain what 'destructive' means here (e.g., potential side effects like triggering actions on a webpage) or mention rate limits, permissions, or error handling. With annotations covering safety, the description provides some basic context but lacks depth.

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 extremely concise—a single, clear sentence that directly states the tool's purpose without unnecessary words. It's front-loaded and wastes no space, making it easy for an agent to parse quickly. Every word earns its place, adhering perfectly to conciseness principles.

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?

Given the tool's low complexity (1 parameter) and rich annotations (destructiveHint, openWorldHint), the description is minimally adequate but incomplete. It lacks output information (no output schema), doesn't explain behavioral implications of annotations, and omits usage context. For a destructive tool with siblings, more guidance would improve completeness, but the basics are covered.

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?

Schema description coverage is 100%, with the 'key' parameter fully documented in the schema. The description doesn't add any meaning beyond the schema—it doesn't clarify key naming conventions, special cases, or examples beyond what's in the schema description. Given high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't detract.

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 ('press a key') and the target ('on the keyboard'), providing a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'browser_type' or 'browser_click', which also involve keyboard interactions or input methods, leaving some ambiguity about when this specific key-press action is preferred.

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_type' (for typing text) or 'browser_click' (for mouse actions), nor does it specify contexts such as pressing special keys (e.g., Enter, Escape) or simulating keyboard shortcuts. This lack of comparative context leaves the agent without clear usage instructions.

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