Check checkbox/radio

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose a meaningful behavior: 'No-op if already checked', and clarifies acceptable target forms. However, it omits other relevant behavioral traits such as what happens on failure, whether it waits for the element, return value, or side effects like unchecking a radio's siblings. It is minimally adequate but has clear gaps.

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 three short sentences with no filler. It front-loads the core action, then adds the no-op behavior and targeting options. Every sentence contributes essential information, making it appropriately sized for the tool's simplicity.

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 simplicity, the detailed input schema, and the absence of an output schema, the description is largely complete for correct invocation. It covers the action, the no-op case, and target specification. It could be more explicit about return behavior or error conditions, but those are minor for this type of action tool.

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%, so the baseline is 3. The description adds a small amount of value by summarizing that targets support selectors or getBy* locators and giving an example (getByRole with name), but it does not materially extend parameter semantics beyond what the schema already documents for sessionId, target, or timeoutMs.

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 a specific verb and resource: 'Checks a checkbox or radio input in the session page.' This distinguishes it from the sibling tool 'uncheck' and other interaction tools like 'click' by naming the exact input types it acts on. It also adds a useful behavioral fact ('No-op if already checked') that reinforces its purpose.

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 implies usage by naming the target input types and notes that it is a no-op when already checked, which tells the agent when the call is unnecessary. However, it does not explicitly contrast with alternatives like 'click' or 'uncheck', nor does it state when to prefer this tool over them. The targeting guidance (selectors or getBy* locators) is practical but not usage-selection guidance.

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