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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and external-data profile is covered. The description adds the freshness signal 'current' and the shape of a story card, but the field list largely restates what the output schema already carries, and there is no note on how volatile or how large the feed is.

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, zero padding, with the primary behavior front-loaded and the disambiguation rule placed after it. 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 parameterless feed tool with an output schema and read-only annotations, this is close to sufficient: purpose, payload, and the alternative are all present. The only minor gap is any indication of feed size or refresh behavior, which an agent might want but can discover from the response.

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 takes zero parameters, which sets the baseline at 4. The description is consistent with that by implying no filtering is possible and directing agents that need scoping to a different tool, so nothing is left ambiguous.

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 ('Return current Yahoo Sports home-page story cards') and enumerates the payload fields an agent will get back. The final sentence names the sibling it is not, so it is distinguishable from yahoo_sports_topic_news without opening either schema.

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?

Gives an explicit routing rule: this tool is for the home page, and yahoo_sports_topic_news is the alternative when a sport-scoped page is wanted. That is a when-to-use-this / when-to-use-the-other pair, which is exactly what an agent needs to choose between two similar feed tools.

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