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

Annotations only cover readOnly and openWorld; the description adds real operational context an agent could not otherwise know: no API key needed, pay-per-call at $0.002 USDC via x402 across Base/Solana/Arc, and failed calls are free — that is material for deciding whether to call. It stops short of ordering, rate limits, or what happens on an empty keyword match, so it is not exhaustive.

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 short sentences with zero filler: source and scope first, freshness constraint second, payment/auth last. Nothing is repeated from the schema at length and every sentence carries information the agent needs.

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 two-parameter read-only feed with an output schema and full schema coverage, the description covers what the tool returns, its freshness limit, auth requirements, and cost model. Minor gaps remain around result ordering and behavior when the keyword matches nothing, but nothing essential 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 description coverage is 100%, so the schema already defines both q (all words must appear, max 200 chars) and limit (1–30, default 10). The description restates the title/summary matching for q but adds nothing about limit or result-count behavior, so it sits at the baseline.

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 verb (search), a specific resource (CNBC top news) and the exact source (CNBC's public RSS feed) with a note that filtering applies to title/summary. The publisher is named explicitly, which is the only thing that separates it from the dozens of sibling search_*_articles tools, so an agent can route to it without opening the schema.

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" implies a freshness constraint and the keyword behavior implies when it is appropriate, but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as search_google_news or the other publisher feeds. The agent must infer that this is the CNBC-specific choice rather than a general news search.

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