get_amazon_delivery_time

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

With no annotations, the description carries the full burden and does so: it discloses cost (2 points/call), latency (~5s), the address/zipcode dependency of results, the fallback when zipcode is omitted, and that unavailable extra fields come back as empty strings rather than erroring. This is unusually complete behavioral context for a mutation-free lookup.

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?

Labeled sections (Use when / Don't use / Returns / Cost) put the decision-relevant content first and every sentence earns its place. Dense but zero filler.

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?

There is no output schema, yet the description spells out the return path (data.json[0].data.results[0]) and the incremental fields (frequentlyReturnedItem, leadTime, delivery{...}), so an agent knows what to expect. Combined with cost and the zipcode caveat, nothing needed to invoke it correctly is missing.

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 the baseline is 3; the description goes beyond it by explaining that delivery estimates are dependent on the address/zipcode and that the backend substitutes a country-matched ZIP when omitted, which is meaningful semantics the schema only hints at.

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 ('Return the full listing detail for one ASIN plus address-dependent delivery estimates') and immediately distinguishes itself from the sibling get_amazon_product by scope and cost. An agent can tell exactly what this returns versus ordinary product detail 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?

Provides explicit 'Use when' triggers (estimated arrival, free vs paid timing, fastest option, lead time, high-return warning) and an explicit 'Don't use' clause with the named alternative and its cheaper cost. Routing is fully determined.

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