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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true, destructiveHint=false), so the bar is lower, yet the description adds substantial context beyond them: conditional billing ('Charged only if at least one page was read'), exact price ($0.005 USDC), payment rails (Base, Solana, Polygon, Arbitrum) and the x402 payment mechanism, plus the return format. This is exactly the kind of cost/auth detail annotations cannot express.

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?

Front-loaded with purpose and the sibling distinction before any pricing detail, and each sentence does work. It is dense and the payment-rails enumeration plus the free-sample example push length, but for a paid tool that information is load-bearing rather than filler.

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 no output schema, the description still specifies the return shape (title, URL, snippet, already-read Markdown) and the per-page character cap, plus cost and payment requirements. Nothing an agent needs to call this correctly and predict its result 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 0%, so the description carries the full burden and does: query (required), source ('web' default or 'news'), count (1 to 5, default 3), max_chars per page (500 to 20000, default 4000). Every parameter gets its default, range and meaning, which the bare schema does not convey.

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+resource with scope: searches Wikipedia ('web') or recent news ('news') and returns the top 1-5 result pages already read as clean Markdown with title, URL and snippet. It explicitly differentiates itself from siblings, declaring 'Not a general web search engine' and contrasting with web-search, so an agent can distinguish it from web_search, webpage_reader and web_read_batch without opening a 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?

Gives an explicit trigger ('Answer a question when you have no URL yet'), an explicit alternative with its selection condition ('If links and a short summary are enough, web-search is cheaper'), and a value framing ('Replaces one search call plus several page reads'). When-to-use, when-not-to-use and the alternative are all named.

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