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

Beyond the readOnly/openWorld annotations it discloses ordering (newest first), de-duplication, wire tagging, the exact returned fields ('Headlines, links, dates and summaries only'), the auth model ('Public RSS, no key'), and the billing model with a failure carve-out ('$0.003 in USDC per successful call... failed calls are not charged'). These are behaviors the annotations cannot convey and that materially affect how an agent plans a call.

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?

Sources, behavior and pricing are front-loaded in a compact block, and every clause carries signal. Minor deductions for the garbled fragment 'from its public' in the related-tools sentence and for stacking three concerns (catalog notes, alternatives, x402 billing) into one paragraph.

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 return values need not be explained, and annotations cover the safety profile; the description fills the remaining gaps an agent needs — sources, dedup/ordering, auth, and per-call cost with failure handling. Nothing required to call it correctly 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 q, limit and wires are already fully documented with defaults and constraints. The description only restates the keyword-filter scope ('title/summary') and notes each item is tagged with its wire, adding little beyond the schema; baseline 3 is appropriate.

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 the exact resource set (PR Newswire all-news, Business Wire M&A, Newswire.com) and the aggregation behavior (merged, de-duplicated, newest-first), which is precisely what separates it from the single-source siblings like search_prnewswire_press_releases and search_doj_press_releases. An agent can tell this is a multi-wire press-release feed reader 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?

It explicitly routes two sibling cases ('search_prnewswire_press_releases when you need PR Newswire health-category...', 'search_doj_press_releases when you need US DOJ press releases') and states the prerequisite that no key is needed. It gives no guidance against the many other news search siblings (search_google_news, search_news_across_the_web, search_pr_newswire), so routing is clear but not exhaustive.

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