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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds that it returns organic results, which is a useful behavioral trait beyond annotations. It does not discuss pagination, result count, or any quirks, but the annotation coverage lowers the burden. No contradiction with annotations.

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 two concise sentences with zero wasted words. The core purpose is front-loaded, and the privacy differentiation follows immediately. 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?

For a simple search tool with fully documented parameters, the description adequately states what it does and the nature of results (organic). Given there is no output schema, it could mention more about the return format or any 'light' limitations, but it is sufficient for an agent to decide whether to call it. Slightly more detail on output would push it to a 5.

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 all three parameters (q, locale, time_period) are fully documented in the schema itself. The description adds no additional parameter-specific meaning, so the baseline score of 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 and resource: 'Search the web using DuckDuckGo' and notes 'Returns organic results.' It differentiates from Google by calling itself a 'Privacy-focused alternative to Google,' which helps distinguish it from google_search_light. However, it does not explicitly differentiate from other search engines like bing_search, so it falls short of a perfect score.

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 provides clear context by positioning the tool as a privacy-focused alternative to Google, implying it should be used when privacy or unbiased results matter. It does not explicitly state when not to use it or list alternative tools, but the privacy angle is a meaningful usage signal for an agent.

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