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

Annotations already declare readOnly and openWorld, so the description is free to add the traits that matter: a hard cap of 5 topics per call and an x402 cost of $0.003 USDC per call. Pricing and rate/cap constraints are exactly the behavioral context an agent needs before invoking. It stops short of describing errors or rate limits.

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?

Three tight sentences that front-load the resource and scope, then the positioning, then the cost. Efficient with little waste, though the simultaneous 'free' and '$0.003 USDC per call' framing is slightly ambiguous.

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 usefully enumerates the returned fields, and it discloses the cost and topic cap. However, for a 3-parameter tool at 33% coverage, the semantics of 'days' and 'lang' are left entirely unspecified, leaving a real gap.

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 only 33%: 'articles' is documented as comma-separated titles and the description reinforces the 5-topic cap, but 'days' and 'lang' are undocumented in both schema and description. The description adds real value for the topics parameter but does not compensate for the two undocumented parameters.

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: Wikipedia pageview interest over time for up to 5 topics, and even enumerates the returned metrics (daily views, average, trend percent, peak day). It distinguishes itself conceptually from search-trend data, though it never names a concrete sibling tool, so it falls short of a 5.

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 clear context for use ('comparing brands, coins, people and products') and positions itself as an alternative to search-trend data. No explicit when-not-to-use or named alternative sibling is provided, so it is clear context without exclusions.

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