light

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

With no annotations, the description carries the full burden. It does disclose the important behavioral trait that the change persists across all existing AND future pages, but says nothing about reversibility (calling 'dark'), whether the setting is per browser context, or whether a reload is needed for existing pages.

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?

One short sentence with the action and scope front-loaded and no wasted words. Slightly terse for a state-changing tool, but structurally sound.

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 one-parameter, no-output global preference toggle this covers the essentials, but omits how to revert the change and whether the persistence is per-tab, per-context, or global, which matters given the 'tab' parameter.

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 coverage is 100% and the single 'tab' parameter already documents itself as defaulting to the current tab. The description adds nothing about 'tab' and its 'all existing and future pages' phrasing is neutral-to-slightly-tensioned with a tab-scoped parameter, so baseline 3 applies.

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 ('Persist') and resource ('light color-scheme') plus the scope of effect. It is implicitly distinguished from the sibling 'dark' tool by naming the light scheme, though it never explicitly says 'use dark to switch back'.

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 scope clause ('all existing and future pages') implies this is a global preference toggle, from which an agent can infer the dark counterpart, but there is no explicit when-to-use/when-not statement or named alternative.

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