Playwright MCP

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

Annotations provide key behavioral hints: destructiveHint=true (indicating potential changes), readOnlyHint=false (confirms it's a mutation), and openWorldHint=true (suggests dynamic environment). The description adds minimal context beyond this, stating the action but not elaborating on effects like UI state changes or error conditions. No contradiction with annotations exists.

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 directly states the tool's purpose without unnecessary words. It is front-loaded and wastes no space, making it easy to parse quickly.

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 complexity of a drag-and-drop operation in a browser context, the description is minimal. Annotations cover safety and environment aspects, but no output schema exists, and the description doesn't address return values, error handling, or interaction nuances. It's adequate but leaves gaps for a tool with destructive potential.

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 documentation for all four parameters (startElement, startRef, endElement, endRef). The description adds no additional parameter semantics, such as explaining the relationship between 'element' and 'ref' parameters or usage examples. Baseline score of 3 is appropriate given high schema coverage.

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 ('perform drag and drop') and specifies the relationship ('between two elements'), which is more specific than just the tool name. However, it doesn't explicitly differentiate from sibling tools like browser_click or browser_hover that also involve element interaction, though the drag-and-drop action is distinct.

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 like browser_click or browser_hover for similar element interactions. It lacks context about prerequisites (e.g., needing element references from a snapshot) or scenarios where drag-and-drop is appropriate over other methods.

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