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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read/open-web profile is covered. The description adds the source ('public news page') and the limit cap, but says nothing about freshness/caching, ordering, or upstream rate limits. Adequate, but modest value beyond structured fields.

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?

Two sentences with zero filler; the core fetch semantics and the limit bound come first, and the routing to alternatives follows. Every clause 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 one-parameter, read-only feed tool with an output schema, an openWorld annotation, and explicit sibling routing, the description covers what an agent needs to select and call it correctly. Return field details are legitimately left to the output schema.

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% and the single parameter's default (20) and max (50) are stated identically in the schema. The description repeats rather than extends that information, so baseline 3 is correct.

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 ('Fetch') and resource ('recent article cards from CoinGecko's public news page'), which pins the return shape to news article cards rather than generic news. It is instantly distinguishable from sibling news-feed tools that pull headlines or full articles.

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?

Explicitly routes alternate intents: coingecko_learn_articles for educational guides and coingecko_coin_analysis for per-coin analysis. Both the when-to-use-this and when-to-use-something-else are stated, leaving nothing to inference.

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