costco_product_availability

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

With no annotations, the description carries the full burden. It discloses that the data is public and sourced from Costco's fulfillment backend, which implies no authentication required. However, it does not mention error handling, rate limits, or caveats about delivery estimates, so it only partially covers behavioral traits.

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?

The description is two concise sentences, front-loaded with the core action ('Get a Costco product's delivery estimate') and then elaborating on the output. No unnecessary words or repetition.

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 simple 3-parameter tool with no output schema, the description is sufficient. It specifies the required inputs (product id, destination) and the output (stock and delivery status), which is enough for an agent to select and invoke it. It does not detail the return format, but this is acceptable given the tool's low complexity.

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 input schema already describes all three parameters (id, state, postal_code) with 100% coverage. The tool description only adds that state and postal_code define a 'delivery destination,' which reinforces but does not extend the schema. Baseline of 3 is appropriate since the schema does the heavy lifting.

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 'Get a Costco product's delivery estimate' and further explains it returns stock and estimated-delivery status for a destination. This is a specific verb+resource combination that distinguishes it from sibling tools such as costco_product, costco_search, and costco_product_reviews.

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 provides clear context: use this tool when you need stock and delivery estimate for a specific Costco product at a given US destination. It does not explicitly mention alternatives or exclusions, but the intended usage is unambiguous given the tool's name and description.

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