Playwright MCP

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

Annotations already provide readOnlyHint=false (mutation), destructiveHint=true (potentially destructive), and openWorldHint=true (dynamic environment). The description adds minimal behavioral context beyond this—it implies batch operation ('multiple form fields') but doesn't disclose risks like form submission side effects, error handling, or that 'ref' requires exact page snapshot references. No contradiction with annotations.

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?

Extremely concise at three words, front-loaded with the core action. Every word earns its place—'fill' specifies the action, 'multiple' indicates batch capability, and 'form fields' identifies the target. No wasted verbiage.

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 destructive mutation tool (destructiveHint=true) with no output schema, the description is inadequate. It doesn't explain what happens after filling (e.g., form submission, validation), error scenarios, or dependencies (e.g., requires browser_snapshot for 'ref'). Given the complexity and risk, more context is needed.

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 detailed parameter documentation in the schema itself. The description adds no additional meaning about parameters beyond implying batch processing ('multiple'), which is already clear from the array type in the schema. Baseline 3 is appropriate as the schema carries the full burden.

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 'Fill multiple form fields' clearly states the verb ('fill') and resource ('form fields'), distinguishing it from siblings like browser_type (single field typing) or browser_select_option (dropdown selection). However, it doesn't explicitly mention that this is for browser automation or that it handles multiple field types, which the schema reveals.

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?

No guidance on when to use this tool versus alternatives like browser_type (for single text fields) or browser_select_option (for dropdowns). The description doesn't mention prerequisites (e.g., needing a browser snapshot first) or exclusions (e.g., not for non-form elements).

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