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

Annotations only declare readOnly/openWorld, but the description adds genuinely non-obvious behavior: no API key required, a $0.002 USDC charge per successful call via x402 on Base/Solana/Arc, and that failed calls are not charged. Payment and auth requirements like these are exactly what an agent needs before invoking the tool.

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?

Three compact sentences: what it is and its filter scope first, then the 'latest items only' constraint, then access/cost terms. Nothing is redundant or buried.

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 and the input schema fully documents both parameters, so the description's remaining burden is access, cost, and scope — all covered. An agent can decide and invoke correctly from this.

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 both parameters are already documented; the schema even specifies that all words must appear and the 1-30 range. The description only restates the filter fields, and its mention of 'categories' is slightly broader than the schema's 'title or summary' — marginal added value, so baseline 3.

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 names a specific source (gCaptain maritime news) and its retrieval channel (public RSS feed), with a keyword filter scoped to title/summary/categories. That is specific enough to separate it from the many other news-search siblings, though the verb is implied by the tool name rather than stated.

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?

'Latest items only' and the keyword-filter scope imply when the tool fits, but there is no explicit when-to-use or when-to-prefer-an-alternative guidance (e.g., vs. search_google_news or search_news_across_the_web for broader coverage). Usage must be inferred from the niche source.

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