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

The annotations already declare readOnlyHint=true and idempotentHint=true, so the read-only nature is covered. The description adds real behavioral detail by disclosing the temporal filter (past and future promotions are not returned) and the fields included, but it is silent on how the brand is resolved given there are zero parameters, and says nothing about ordering or result volume.

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 sentences, front-loaded with what is returned and immediately followed by the exclusion rule. Every sentence carries information an agent needs and there is no filler.

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 parameters and no output schema, the description carries the full burden and largely meets it: it names the returned fields (conditions, dates, codes) and the temporal scope. The only meaningful gap is the unexplained brand context that determines what gets returned.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate. The one implicit input, the brand context, is not explained, which keeps this below a 5.

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 gives a specific verb and resource (promotions and discounts of this brand) and narrows scope to those valid today, so an agent can tell it apart from an offer-detail tool. It stops short of explicitly differentiating itself from siblings such as search_offers or get_offer, leaving the boundary to be inferred.

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 implied by the scope: fetch current promotions for this brand. There is no statement of when to prefer it over related tools such as search_offers or get_offer, and no explicit when-not guidance beyond the fact that expired or future promotions are excluded.

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