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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds value beyond them by naming the data source (HMRC UK Integrated Online Tariff) and disclosing the shape of the returned entries, which the annotations say nothing about.

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 short sentences, front-loaded with the purpose, then usage routing, then provenance and an example call. Every sentence earns its place and nothing is padded.

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 two-parameter read tool with rich annotations but no output schema, the description covers purpose, routing, source and the salient fields of each returned record. The only gap is the absence of any pagination or truncation guidance around the limit parameter's 200 cap.

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 description coverage is 100%, so both the heading format and the limit default/max are already documented in the schema. The description only restates the heading as 4-digit with an example call, adding no format, validation or edge-case meaning beyond the structured fields. Baseline 3 applies.

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 ('List the commodity codes that sit under one 4-digit UK tariff heading') and enumerates the returned fields (descriptions, indent level, declarable flag). It also distinguishes itself from uktariff_search by framing this as the downstream drill-down step, so an agent can tell the two apart 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?

Explicitly says when to reach for it: 'drill down after uktariff_search returns a heading' or 'enumerate the options within a product family before picking a code.' That is clear positive context, but it never states a when-not condition or contrasts itself with the uktariff_commodity sibling, so it stops short of the 5 bar.

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