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

Annotations already include readOnlyHint: true, and the description adds context about the type of information returned (coverage details, languages, regions, usage terms). It mentions usage terms, which is extra behavioral context beyond annotations. No contradiction with annotations, and it uses the annotation coverage appropriately.

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 sentences, front-loaded with the purpose and followed by usage guidance. Every sentence adds value, with no redundancy or filler. It is concise and well-structured.

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 low complexity (no parameters) and the presence of an output schema, the description fully covers the tool's scope: what it does, what it covers, and when to call it. It provides all necessary context for an agent to decide whether to invoke it, without needing to describe return values since the output schema exists.

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 tool has zero parameters, so the baseline score of 4 applies per the rubric. The description does not need to explain parameters, and it correctly focuses on the tool's purpose and output content.

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 states a specific verb and resource: 'Describe what the Trend News Agency archive covers.' It enumerates the exact content areas (language editions, canonical hosts, regions, beats, usage terms), which clearly differentiates it from sibling tools that fetch articles or search. This is a distinct, well-defined 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 explicitly says 'Call this before a first search to find out whether Trend is a useful source for a question, and which language edition to search.' This gives clear context on when to use it, but it does not explicitly mention alternatives or when not to use it, so it falls slightly short of the highest rating.

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