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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds behavior beyond that: results are ordered newest first, and since matches stories that were published OR updated, not just published — a distinction an agent could easily get wrong. It does not discuss paging or result size beyond the limit parameter.

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 filler, with the core identity of the tool front-loaded ahead of the two optional narrowing modes. Every clause corresponds to a parameter or a behavioral fact.

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 three-parameter, fully documented read tool with no output schema, this covers what an agent needs in order to call it correctly and to chain it into a polling loop. The only omission is any hint about the shape of a returned story, which the get_story sibling presumably handles.

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 coverage is 100%, so the baseline is 3, but the description earns an extra point by explaining how since should be sourced (the as_of of your last reply) and that tickers are OR-matched narrowing filters. That is real meaning the schema does not carry.

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 newest Raydn stories, newest first" names a specific resource and its ordering, which is enough for an agent to distinguish this recency feed from a query-based search. It stops short of naming search_news or get_story as the contrasting alternatives, so the differentiation is implied rather than stated.

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 gives concrete usage context: narrow by tickers for a topic-scoped feed, or pass since to poll for what is new or updated. The parenthetical "the as_of of your last reply" is a genuinely actionable calling pattern. It does not state when to prefer search_news instead, so no explicit exclusion is offered.

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