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

Annotations only cover readOnly and openWorld, but the description adds substantial behavior beyond that: data lags by about a day, bots/unknown agents are excluded, and the output includes totals, peak day, and a first-vs-second-half change. It also discloses pricing ($0.002 USDC via x402) and that failed calls are not charged, which is critical invocation context.

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 the core purpose, then mode behavior, then lag/selection caveats, then pricing. Every sentence carries information, though the first sentence is densely packed with parenthetical clauses that could be split for scannability.

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 6-parameter tool with an output schema, it covers everything an agent needs: input limits, mode semantics, data freshness, exclusion rules, and cost/charging behavior. Since an output schema exists, it needn't detail return shape, and its summary of aggregates is a bonus.

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 already 100%, so the baseline is 3, but the description adds meaning the schema lacks: the hard limits (up to 5 articles, date range at most one year) and the mode-dependent role of 'from'. These constraints materially affect correct invocation.

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 (daily/monthly page views for Wikipedia articles) with scope qualifiers (up to 5 articles, one edition, date range). An agent can immediately tell this apart from the sibling 'wiki' and 'wikidata' tools.

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?

Clearly explains the two modes ('series' vs 'mode=top lists the most viewed articles of one day') and the operating constraints (max 5 articles, date range at most one year). It does not explicitly route the agent away from the sibling 'wiki'/'wikidata' tools, so it falls short of full when-not guidance.

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