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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and openWorld=false, so safety is covered. The description adds genuinely useful behavioral context beyond that: output is headline + summary only, source_url is mandatory, and it explicitly never returns full third-party text — a licensing/content constraint an agent should know. It says nothing about rate limits or freshness/latency, keeping it from a 5.

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?

A single tightly packed sentence plus a short usage clause, with the resource and returned fields front-loaded and zero wasted words.

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?

With an output schema present, return-value explanation is not needed, and the content constraints (summary-only, mandatory source) cover the key disclosure. What remains unstated is the alternative route (public_search_news) and any rate/pagination behavior, so it is strong but not fully complete.

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% (ticker, limit, days_back all documented with defaults and maxima), so the schema carries the parameter burden. The description adds no syntax, default, or range detail beyond it; baseline 3 is appropriate.

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?

Names a specific resource and scope ('Latest news for a ticker') plus the returned shape (headline, short summary, source_url). It implicitly separates itself from the generic public_search_news sibling by being ticker-scoped, but never says so outright, so it stops short of full sibling differentiation.

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?

'Use to ground a market read in recent, attributable news' gives a concrete when-to-use scenario. It offers no exclusions or alternative routing (e.g., when to prefer public_search_news over this tool), which caps it at 4.

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