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

readOnlyHint=true already covers the safety profile, and the description adds real content context: what entity lists come back, which code identifies each, and that all three are returned by default. It stops short of stating whether the lists are static or paginated, but for a small reference dataset that gap is minor.

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 sentence, front-loaded with the resource, then the identifying codes, then the optional narrowing parameter. No filler or restatement of the title.

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 zero-required-parameter read-only lookup with no output schema, the description sufficiently describes the payload shape (lists plus their codes) so an agent knows what it will receive. Only the response envelope/ordering is left unspecified, which is low risk here.

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% and the `include` parameter is already documented, so the baseline is 3. The description goes beyond it by explaining what each list contains and which code field maps to it, giving the enum values meaning the schema alone does not.

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 (the countries, languages and topics World Feed Monitor covers) and the exact code formats returned (iso_2/iso_3, language code, topic key). It reads as a reference-data lookup, which implicitly separates it from the news/search siblings, though it never names them.

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?

Usage is only implied: the mention of 'codes to filter by' suggests it should be called before search_news, but the description never says when to use this versus get_sources or get_latest_news, nor any exclusions. The only explicit instruction is about the optional `include` parameter.

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