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

Annotations already declare readOnlyHint=true. The description adds behavior beyond that: a one-day window, newest-first ordering, 25-item pagination, and the fact that each article includes publisher and URL. It stops short of describing rate limits or whether empty results are possible.

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 tight sentences; the core scope leads and the optional filters and returned fields follow. No boilerplate or repetition.

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 read-only, fully documented 5-parameter tool with no output schema, the description covers window, ordering, page size, filters, and returned fields. It could add a bit more routing context against search_news, but nothing needed to invoke it correctly is missing.

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 schema already documents page, source, country, language, and macro_category. The description restates the filterable dimensions (topic, country, language, publisher) without adding syntax or constraints, so baseline 3 applies.

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 resource and scope: newest articles from the last day, newest first, 25 per page. It does not explicitly name search_news as the alternative, so sibling differentiation is only implicit.

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 last-day, newest-first framing implies when to use it for recent news, and it notes optional narrowing by topic, country, language, or publisher. But it never states when to prefer search_news or get_sources, nor any exclusions.

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