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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety is covered. The description adds genuinely useful context that this is a computed estimate from the shop's time rather than a GPS-derived figure, setting accuracy expectations, but says nothing about failure modes or freshness.

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 short clauses with zero waste, and the substantive answer (what 'expected time' means) is front-loaded ahead of the clarifying caveat.

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 composition of the returned value (chosen time + delay + minutes left). For a simple read-only lookup whose parameters are fully documented in the schema, this is close to complete, missing only how to interpret the result when no ETA exists.

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% and both parameters (shop, order_id) are already documented with their sources (find_shops, place_order/my_orders). The description adds nothing about parameters, so the 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?

The description states the resource precisely: the expected ready-for-pickup or delivery time, derived from chosen time plus shop delay. An agent can distinguish it from status tools like get_delivery_status or check_delivery by the 'estimate, not GPS' framing, though it does not name a sibling explicitly.

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: call this to learn when an order will be ready or delivered. There is no explicit when-to-use/when-not guidance and no named alternative (e.g. get_delivery_status for actual progress vs. ETA), leaving the agent to infer the routing.

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