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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and open-world nature are covered. The description adds the useful behavioral detail that the returned offers carry a spend threshold and item value, but says nothing about data freshness, what happens with an unknown restaurant_id, or how the lat/long affect results.

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?

A single, front-loaded sentence that names the resource first and the offer categories second. No filler, though the trailing 'with spend threshold and item value' is slightly dense and could be polished.

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?

An output schema exists, so return-value shape need not be explained, and the description conveys the kinds of promotions returned. However, for a 3-required-param lookup it omits any usage context (why coordinates are needed alongside the restaurant_id) and any failure behavior.

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 all three parameters (restaurant_id, latitude, longitude) are self-documented as Required. The description adds no syntax, format, or constraint detail beyond what the schema already carries, so 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+resource: returns currently active promotions for a Grubhub restaurant, and enumerates the promotion types (free items, BOGO, spend-and-save) with spend threshold and item value. This clearly distinguishes it from the brand's menu, reviews, availability and search siblings, though it does not name them 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?

The description implies when the tool applies (you want a specific restaurant's active promos), but there is no explicit when-to-use vs alternative guidance and no stated prerequisites, such as requiring a valid restaurant_id paired with diner coordinates.

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