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

Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint, so the safety profile is covered; the description's 'Read-only' is consistent though redundant. It does add value beyond annotations by naming the backing endpoint and by surfacing the shape of the returned data (dates, benefits, usage counts, revenue, triggers), which is meaningful given there is no output schema.

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 dense sentence that front-loads the core action and then the returned fields, followed by a short read-only/endpoint note. Every clause carries information, though the long parenthetical field list is slightly list-heavy rather than prose.

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?

With no output schema, the description compensates by describing the returned promotion structure (name, dates, benefits, usage/revenue, limitations, triggers), which is what an agent needs to interpret results. Minor gaps remain: no mention of pagination or result limits, and nothing about how test_mode affects results.

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 is one optional parameter (test_mode) and schema description coverage is 100%, so the schema already fully documents it. The description adds no parameter-level detail (e.g., that test_mode data is isolated from live revenue figures), so the 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 ('List promotions') and immediately clarifies scope with the parenthetical 'checkout discounts and bonus credit', which disambiguates the term 'promotion' from marketing/other concepts. It also enumerates what each promotion contains (dates, benefits, usage, limitations, triggers), so an agent knows exactly what this returns versus the sibling get_* tools.

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: it lists promotions and notes 'Read-only. GET /promotions.' There is no explicit guidance on when to use this versus giftup_get_order or giftup_list_transactions (e.g., 'use this to find a promo code before an order lookup'), nor any exclusions or prerequisites.

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