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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the agent knows this is a non-destructive mutation. The description adds only the CSS-selector locating method and adds nothing about behavior when the element is not a checkbox, is already unchecked, or is missing.

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?

A single front-loaded sentence with the action first and the qualifiers after; no filler, no redundancy.

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 two-parameter, simple mutation tool with annotations covering safety and full schema coverage, the description is essentially sufficient. Minor gaps remain around failure behavior and whether the target must be specifically a checkbox, but nothing critical is missing for correct invocation.

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 both parameters (selector, session_id) are already documented in the schema. The description restates the selector idea but adds no syntax, format, or edge-case detail beyond what the schema provides, making the 3 baseline correct.

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 a specific verb and resource ("Uncheck a checkbox") plus the targeting mechanism (CSS selector) and context (browser session), which clearly separates it from browser_check. It never names that sibling, so differentiation is implied by the verb rather than stated.

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 purpose implies when to use it (when a checkbox needs unchecking), but there is no explicit guidance, no prerequisite that a session must already exist, and no pointer to browser_check for the inverse operation.

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