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

Goes well beyond the readOnlyHint annotation by disclosing subscriber-only behavior: articles within the last year return metadata/excerpt with body withheld, while older or free articles return in full. Also instructs the agent to cite the returned url, a practical behavioral requirement.

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?

Packed but not bloated: purpose, return values, parameter selection, access restrictions, and citation requirement all earn their place. Front-loaded with the main action.

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?

Despite having an output schema, the description covers all important nuances: article contents, restrictions for subscriber-only articles, URL/id+lang behavior, and the citation instruction. Nothing important is left to inference for a 3-parameter tool.

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 already documents all three parameters at 100% coverage, so the baseline is 3. The description adds meaningful usage semantics: url is the 'reliable way,' id requires lang, and lang defaults to en/ignored with url. This elevates the parameter guidance.

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?

Description states a specific action ('Fetch one Trend News Agency article in full') and enumerates the returned content (headline, byline, dateline, tags, body). The URL-vs-id+lang distinction and access restrictions separate it from sibling list/search/page tools.

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?

Provides clear guidance on selecting URL vs id+lang and notes that lang is ignored when url is given. It does not explicitly mention alternative sibling tools for cases like listing or searching, but the single-article scope is strongly implied.

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