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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description builds on that by adding the OAuth requirement and the anonymous-caller authorization prompt. This is meaningful behavioral context beyond the structured annotations, though it does not cover potential failure modes or empty results, which are minor for this simple read-only tool.

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 compact and front-loads the main purpose before usage guidance and auth details. A few phrases, such as 'Scope: favorites' and the general note about comparison tools, add useful context but are slightly redundant or tangential. Overall it is efficient without being bloated.

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?

Given the tool has no parameters, no output schema, and rich annotations, the description covers all necessary operational context: what it returns, when to use it, how to pair results with another tool, and the auth requirement. Nothing critical is missing for correct selection and invocation.

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?

There are zero parameters and schema description coverage is 100%, so the schema carries no parameter burden. The description adds useful output context by stating the returned store_id, which supports the recommended pairing with get_cashback_rates_by_store_id. This meets the baseline for a no-parameter tool.

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 uses a specific verb and resource: 'Returns the signed-in user's favorite stores (with their store_id).' It clearly distinguishes this from sibling tools like get_my_alerts and get_my_profile by focusing on favorite stores, and it also notes the store_id output that enables downstream use. This is unambiguous and easy for an agent to act on.

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 explicitly names trigger phrases ('my favorites' or 'my saved stores') and gives a direct next-step pairing with get_cashback_rates_by_store_id. It also clarifies the auth boundary by stating that comparison tools work without signing in, helping the agent choose appropriately among siblings.

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