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

With no annotations, the description carries the full burden; it discloses source coverage and the 'up to 40 hits' result cap, which is useful behavioral context. However, it omits return structure, ordering, failure behavior, and subscription/rate-limit implications beyond the vague 'PRO' label.

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?

The description is very short and front-loads the core action and scope. The unexplained 'PRO.' prefix adds ambiguity without enough payoff, but otherwise the sentence is efficient.

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 simple two-parameter search tool, it gives the data source and result cap. But with no annotations and no output schema, it should say more about what a hit contains, how results are ordered or limited, and whether subscription/auth is strictly required.

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 only 50%: access_token is documented in the schema, but keyword is not. The description adds only that keyword filtering exists, without explaining matching semantics (title/body, multiple terms, case, etc.).

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 action (keyword filter/search) and resource (major NHK RSS categories), with a useful result cap. It does not explicitly distinguish itself from siblings category or top_headlines, and the leading 'PRO.' is unexplained.

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?

There is no guidance on when to choose headline_search over category or top_headlines. The only hint is the 'PRO' label, which is not explained as a precondition or exclusion.

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