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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral context: it lists the specific types of content returned, notes that results are conditional ('when available'), and states the data source and that no auth is required. This goes beyond annotations without contradicting them.

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 sentences, front-loaded with the primary action and content list, followed by use case and data source. There is no redundant wording or unnecessary detail, making it efficient and easy to scan.

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 single-parameter tool with an output schema and safety annotations, the description provides all essential context: what it returns, when to use it, and the underlying API source. No critical information for correct invocation is missing.

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 input schema fully documents the single 'query' parameter with a description and examples, achieving 100% coverage. The tool description does not add new parameter-level semantics beyond the schema; it merely reinforces the use case. Per the baseline rule, a 3 is appropriate when the schema carries the parameter information.

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 the tool returns a DuckDuckGo Instant Answer digest and enumerates its contents: Wikipedia-sourced abstract, direct answer, dictionary definition, entity type, and infobox facts. This specific list distinguishes it from generic web search and the related_topics sibling. It also names the intended use case: quick factual lookups on well-known topics.

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 when-to-use guidance ('Best for quick factual lookups on well-known topics, people, places, and things'), which helps an agent decide to invoke this tool. However, it does not explicitly state when not to use it or name alternatives like duckduckgo.search.related_topics, so the guidance is clear but lacks exclusions.

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