Playwright MCP Server

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

Annotations indicate destructiveHint=true (implying changes to browser state) and readOnlyHint=false (confirming it's a mutation). The description adds no behavioral context beyond this—it doesn't specify effects (e.g., whether resize is immediate or affects all tabs), permissions needed, or error conditions. Since annotations cover the safety profile, the description meets the lower bar but adds minimal value.

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, front-loaded sentence with zero waste—'Resize the browser window' is perfectly concise. Every word earns its place, and there's no redundant or verbose phrasing. This is an exemplar of efficient communication.

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 moderate complexity (a destructive mutation with two parameters) and rich annotations (covering safety), the description is minimally adequate. However, with no output schema and many sibling tools, it should ideally include more context (e.g., return values or error cases). It's complete enough to understand the basic action but lacks depth for robust agent use.

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 clear parameter descriptions for 'width' and 'height'. The description adds no meaning beyond the schema—it doesn't explain units (e.g., pixels), valid ranges, or default behaviors. With high schema coverage, the baseline is 3, and the description doesn't compensate with extra insights.

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 'Resize the browser window' clearly states the verb ('Resize') and resource ('browser window'), making the purpose immediately understandable. It distinguishes from siblings like 'browser_close' or 'browser_navigate' by focusing on window dimensions. However, it doesn't explicitly differentiate from all siblings (e.g., 'browser_snapshot' also relates to window state), so it's not a perfect 5.

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 prerequisites (e.g., needing an open browser), exclusions (e.g., not for mobile browsers), or context (e.g., use for testing layouts). With many sibling tools for browser interaction, this lack of guidance is a significant gap.

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