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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the description's real contribution is the cost model: a few free samples per day, then $0.003 USDC per call via x402. That payment/auth context is valuable and not derivable from structured fields, though it doesn't describe failure modes or rate-limit enforcement details.

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?

Two sentences, no waste, front-loaded with what the tool returns before the cost caveat. The pricing sentence earns its place because cost directly affects whether an agent should call repeatedly.

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 an output schema present, return-format explanation is unnecessary, and the description covers scope, granularity, and cost. It is largely complete for a simple read tool, though it omits any note about partner-country ordering or data-source caveats.

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 all three parameters are already documented; description content is largely redundant, restating the code formats and the period unit. The HS2/HS4/HS6/CN8 naming maps digit lengths to nomenclature, which adds slight meaning over the schema's '2, 4, 6 or 8 digits', but not enough to lift it above the baseline.

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: UK imports and exports of one product identified by HS2/HS4/HS6/CN8 code, with explicit granularity and result shape (totals plus top partners with share). The 'one product' framing cleanly distinguishes it from the uk-trade-stats__country sibling without opening either 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?

Usage is implied through the 'one product' scope and the period granularity, but no when-to-use/when-not guidance or explicit alternative (e.g. uk-trade-stats__country or __latest) is named. The pricing note adds operational context but not selection guidance.

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