list_promotions

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

readOnlyHint=true already covers the safety profile, so the description's marginal contribution is the '(metadata only)' disclosure, which usefully tells the agent the response will not contain full promotion details. Beyond that it says nothing about pagination behavior or result volume, and with no output schema it could carry more of that burden.

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 compact sentences with zero filler; the scoping fact ('metadata only') is front-loaded and the pointer to the alternative follows immediately. Every clause earns its place.

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 zero-required-parameter read-only list tool, the description covers the essential: what it returns (metadata only) and where to go for depth. With no output schema, one might want a hint about the shape of the metadata or pagination expectations, but the essential decision inputs are present.

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%, with page, limit, and include_guide all documented including their defaults. The description adds no parameter-level meaning (e.g., what the 'promotion type reference guide' actually contains), so the baseline 3 is correct.

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 and resource ('List all promotions/discounts of the site') plus a scope qualifier ('metadata only'), so the agent knows it is a lightweight enumeration. It routes away from get_promotion, but does not distinguish itself from closely related siblings such as search_promotions, get_active_promotions, or get_promotion_items, which an agent could plausibly confuse it with.

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?

Explicitly tells the agent when to escalate: 'Use get_promotion for full details,' establishing this tool as the summary-level entry point. It gives no guidance on when to prefer it over search_promotions or get_active_promotions, so the routing guidance is clear but incomplete.

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