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

Annotations only declare readOnly and openWorld; the description adds genuinely useful non-obvious context: no API key, a $0.002 USDC charge per successful call via x402 on Base/Solana/Arc, and that failed calls are free. That cost/idempotency detail is exactly the kind of thing an agent must know before invoking. It does not mention rate limits or recency window size, which keeps it off a 5.

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?

Four short clauses, no filler, each carrying a distinct fact (source, filter, recency limit, access/cost). The most decision-relevant scoping information comes first.

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?

With an output schema to explain returns and annotations to cover safety, the description supplies the remaining decision-critical facts: source, freshness limitation, auth model, and per-call cost. Nothing an agent needs before calling 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 coverage is 100%, so both q and limit are already documented; baseline 3 applies. The description does add that filtering targets title/summary/categories, but that slightly diverges from the schema, which says 'title or summary' only — an agent could reasonably expect category-only matches that the schema doesn't support.

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 (Semafor articles) and its origin (public RSS feed) plus the filtering mechanism (keyword on title/summary/categories), which separates it from the many other publisher-specific news siblings like search_bbc_news_articles. It doesn't use an explicit verb, but 'latest items only' pins the scope. Clear enough to select 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?

Usage is implied by the publisher name and the 'Latest items only' constraint, which quietly signals this is not an archival search. There is no explicit comparison to alternatives (e.g. search_google_news or search_news_across_the_web for cross-publisher coverage) and no stated exclusions.

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