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

Adds substantial context beyond the annotations: a concrete price ($0.005/call), USDC wallet billing subject to budget caps, the fact that confirm_over_cap never raises budgets, and a prompt-injection warning that results are third-party data. This explains why readOnlyHint is false (the call spends money).

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-loads the purpose, then pricing, billing, safety and the free alternative in compact fragments. Slightly dense but every clause carries information an agent needs before invoking a paid tool.

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 paid, no-output-schema lookup tool, the critical unknowns (cost, billing, budget behavior, alternative, data trust) are all covered. It could clarify how the optional 'version' parameter narrows results, but that is a minor 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 67% and the description adds little parameter meaning; it only implies 'version' via the listed fact 'versions'. The confirm_over_cap semantics live entirely in the schema, so the description neither helps nor hurts here.

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 concrete resource and the exact facts returned ('versions, maintainers, downloads, dependencies'), so an agent knows precisely what it gets. It does not differentiate itself from the many other lookup siblings, but the scope is unambiguous.

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?

Explicitly routes the agent to 'free_sample' as a free alternative to try before paying, which is real usage guidance. It stops short of stating when NOT to use this tool (e.g. version-specific vs full-package lookups).

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