execute_js

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

With no annotations, the description carries full burden. It discloses synchrony, main frame execution, full DOM/window/page API access, and JSON serialization of return value. Missing details on error handling and side effects, but adequate for most use cases.

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?

Three concise sentences, no fluff. First sentence states purpose, second adds behavioral detail, third provides usage guidance. Every sentence earns its place.

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 one parameter, no output schema, and no annotations, the description is fairly complete. Covers purpose, execution context, and usage guidance. Lacks error handling or security notes, but acceptable for a tool of this complexity.

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 covers 100% of parameters, so baseline 3. Description adds significant value: explains the 'script' parameter with example, async usage ('await'), and how return value is serialized. This goes beyond schema.

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?

Clearly states 'Execute arbitrary JavaScript in the page context and return the evaluation result.' The verb 'execute' and resource 'JavaScript in page context' are specific. It distinguishes from sibling tools by positioning as a last resort.

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?

Explicitly states when to use: 'Use as a last resort when CSS selectors and other tools cannot achieve the interaction.' Provides clear alternatives: 'prefer click, fill_form, and select_option for standard interactions.'

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