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

Goes well beyond the readOnly/openWorld annotations: discloses de-duplication key (headline), sort order (newest first), per-engine status, that only headlines/snippets are returned with no full text, that Google URLs are redirects, and that billing is $0.003 USDC via x402 on Base/Solana/Arc with failed calls not charged. These are the exact operational facts an agent needs before calling.

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?

A single front-loaded block where each sentence supplies distinct value: sources, merge logic, item shape, limitation (no full text), link caveat, and price. No filler and no repetition of the title.

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 three-parameter aggregator with an output schema already present, the description covers everything else an agent would need — coverage sources, dedup/sort semantics, result limitations, and payment terms. Nothing material 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 q, limit and engines are already fully documented including ranges and defaults. The description only indirectly reinforces the engines parameter by naming the three providers and noting they are public/no-keys; it adds no format or edge-case guidance beyond the schema, so baseline 3 applies.

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 and resource (search news across the web) and enumerates the three backends it fans out to (Google News RSS, Bing News RSS, GDELT Context 2.0), plus merge/de-dup/sort behavior. This clearly separates it from single-source siblings like search_google_news, search_bing_search and search_gdelt_news.

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?

The phrase 'in one call' and the explicit list of three sources implies this is the aggregator to prefer over per-source siblings, and the pricing line tells the agent when the cost is warranted. It stops short of explicitly naming alternatives or stating exclusions (e.g. 'use search_google_news for Google-only queries').

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