page_run

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

Discloses important behavior: it runs in the page, supports await, and returns the value of the last expression. It does not mention error handling or side effects, but for a JavaScript-execution tool the central effect is clearly stated, and no annotations were provided to rely on.

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 short, purposeful sentences with no filler. The main verb is named first, followed by usage context and behavioral details needed to invoke the tool.

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?

With no output schema and no annotations, the description explains the return convention and the supported JavaScript capabilities, which is the core missing context. It does not specify error/timeout conventions, but for a fallback automation tool this is still a sufficiently useful definition.

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?

The page parameter is already documented in the schema, while the description adds meaningful semantic for the js parameter: it is a command string that can use await and whose final expression is the result. This compensates for the moderate schema coverage and gives actionable input rules.

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?

States that it executes JavaScript inside a page and returns the result, which is a specific action on a clear resource. It also describes example operations (measuring, scrolling, resizing, multiple steps) and distinguishes itself from the specialized sibling page tools.

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 positions the tool as the fallback for anything the other page_* tools cannot do, giving strong when-to-use guidance. It does not name the specific sibling tools as alternatives, but the exclusion is likely clear enough from the surrounding tool set.

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