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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds the returned field list and the id-consumption pattern, but says nothing about result size, pagination, or whether all sources are returned when unfiltered — a meaningful gap for an open-world lookup.

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 waste: the operation and filter dimensions come first, and the practical consequence of the result (source ids) comes second. Nothing is padded or repeated.

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?

An output schema exists, so the return-field enumeration is a bonus rather than a necessity, and the core behavior is conveyed. The gaps are the accepted filter vocabularies and whether filters are conjunctive — modest but real for a zero-required-parameter filter tool.

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 0%, so the description carries the burden and does name all three parameters as filters over category, language, and country. It adds no value formats or valid vocabularies (e.g. what categories exist, whether country is ISO-3166), leaving the agent to infer from the schema's bare examples.

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 description states a specific verb and resource ('Return available NewsAPI publisher sources') and clarifies the tool's role as a discovery step feeding 'top_headlines' or 'everything'. It is clearly distinguishable from the sibling search tools, though it never states the inverse (that it does not return 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?

The sentence 'use source ids to filter `top_headlines` or `everything`' gives downstream usage context, which implies this is a lookup you call before searching. However, it never says when to call this tool versus simply calling `newsapi_top_headlines` directly, nor whether filters are combinable or what happens with no filters.

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