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

Annotations already indicate readOnlyHint=true and openWorldHint=true. The description adds that it returns up to 5 recent changes and current duty-rate state for scoped codes, and that the full feed is paid. No contradiction with annotations.

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: first states purpose, second covers scoping, limitations, and payment context. No filler; each sentence adds value.

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?

Given that an output schema exists, the description adequately explains inputs (HTS, since), output (up to 5 changes + current rate), and limitations (free preview, 5 items). The mention of paid alternatives sets expectations for completeness.

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% for both parameters (hts and since). The description adds examples for hts (e.g., '6109') and mentions its role in scoping, but adds little to the 'since' parameter beyond the schema description. Baseline 3 is appropriate.

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?

The description clearly states 'Free preview of recent US import-tariff changes', using specific verb 'preview' and resource 'tariff/HTS changes'. It also mentions optional HTS code scoping and limit of 5 changes, fully distinguishing from sibling tools like depwatch_preview or regwatch_preview.

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?

The description indicates when to use this tool (free preview, optionally scoped) and mentions alternatives ('Full feed and LLM brief are paid via x402'). However, it does not explicitly state when not to use it, but the context of free vs paid is clear enough.

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