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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuinely useful behavioral context beyond that: the required PromoCodes (Read) role and the underlying GET endpoint, which help an agent predict auth failures and understand this is an unfiltered listing call.

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?

Two dense sentences, zero filler. The returned-field list leads, and the auth/endpoint details follow, so the most decision-relevant information is front-loaded.

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 two-parameter read tool with no output schema, the description covers what comes back, the auth requirement and the endpoint — enough to call it correctly. Only the paging/truncation semantics are left entirely to the schema, which is acceptable at full schema coverage.

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% with both `limit` and `promo_code_id` fully documented in the schema, including the default/max and the truncation notice. The description adds nothing about either parameter, so the schema does all the work — baseline 3.

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 names the resource (the club's promo codes) and enumerates exactly which fields come back (code, name, type, value, dates, limits, applicability), so an agent knows precisely what this returns. It doesn't need sibling differentiation because no other tool in the list touches promo codes, but the verb itself is implied by the tool name rather than stated.

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?

Usage is only implied: 'Needs the PromoCodes role (Read)' is a prerequisite, not a when-to-use rule, and there is no explicit statement of when to call this versus another tool. With no promo-code sibling there's little ambiguity in practice, but the description leaves selection logic to inference.

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