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

The annotations already establish this as a non-destructive, closed-world read, so the description adds nothing on the safety axis. It also leaves the key behavioral question open: with zero required parameters, must the caller supply exactly one of the two identifiers, or does calling with neither return an empty set or an error? That is not disclosed.

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 with no filler. It is efficient, but the brevity comes at the cost of the operating rules an agent actually needs, so it is lean rather than optimally structured.

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 lookup tool with two optional parameters, no output schema, and near-identical siblings, the description should state which parameter to pass, whether both may be passed, and what kind of discounts come back. None of that is present, leaving the definition under-specified relative to its ambiguity risk.

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 50%: communityObjectId is documented in the schema while communityReferralCode has no description. The description's phrase 'for a community or referral code' maps loosely onto the two properties and hints that either identifier suffices, which is modest added meaning, but it does not clarify the mutual-exclusivity or precedence rule.

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 sentence names a specific verb ('List') and a specific resource ('auto-applicable plan discounts'), scoped to 'a community or referral code'. This is clear enough to distinguish it from generic discount listings, though it never explicitly contrasts itself with siblings like list_business_discounts or list_community_discounts.

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?

There is no explicit when-to-use guidance, no mention of prerequisites, and no named alternative. An agent facing three closely-named discount-listing siblings gets no help deciding between them from this description alone, only the hint that the result is scoped to a community or referral code.

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