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

Annotations already cover the safety profile (readOnly=true, destructive=false, openWorld=false), so the description's added value is the field semantics: how each modifier is answered and the unit-counting behavior of 'Pick many · qty'/'stepper per choice'. The usedIn=0 warning ('invisible at the till no matter how well it is set up') is a genuinely useful, non-obvious operational caveat.

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 sentences, front-loaded with the core identity of the resource before the routing hint and the field glossary. Dense but each sentence carries information; the answer-mode enumeration is slightly list-heavy but earns its place given no output schema.

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 explains the shape of returned rows (answer modes, usedIn) and flags the usedIn=0 trap. It omits ordering, pagination, and any statement that the list is unfiltered/unbounded, which is the only meaningful gap for a zero-param list tool.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the 4 baseline applies. The prose is spent instead on return-field meaning, which is appropriate for a no-arg list call.

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 ('Every modifier the merchant has') and immediately grounds the abstract term with a concrete gloss ('the questions the till can ask about an item, with their choices and prices'). An agent can tell this is the bulk-list of modifiers and not the single-record or category-scoped siblings.

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?

'Start here for anything about options, add-ons, extras, toppings, sizes, milk, cooking temperature or "how do I let them choose X"' gives strong entry-point routing by intent. It stops short of naming when-not or the alternatives (hub_get_modifier, hub_get_category_modifiers), so the boundary with siblings is implied rather than stated.

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