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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it rejects missing IDs and will not fabricate discounts, totals, orders or delivery guarantees — a real constraint on what the agent can rely on. It says nothing about the shape or size of the returned comparison, which is the remaining behavioral gap.

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 tight sentences with the read/comparison purpose front-loaded and the guardrails after it. The second sentence is telegraphic ("Reject missing IDs; no invented discounts...") but every clause carries information an agent needs. 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?

For a 2-parameter read-only tool with no output schema, the definition is adequate but leaves notable holes: nothing about what a comparison result contains, nothing about how language affects output, and no routing versus the single-offer sibling. It is callable as written, but not fully self-sufficient.

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 0%, so the description carries the burden and only partially meets it: "Reject missing IDs" hints that ids are mandatory and validated, but adds no format or identity semantics beyond the schema pattern. The language parameter is never mentioned, and the 2–4 count bound lives only in the title, not the description.

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 a specific action and resource ("Read side-by-side canonical offer records and terms"), which makes it clear this is a multi-offer comparison/read tool. The title adds the 2–4 cardinality. It stops short of naming the sibling it replaces (e.g. acorn_offer_details for a single offer), so it is clear but not fully differentiated.

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?

"Side-by-side" implies comparison usage, but there is no explicit statement of when to choose this over acorn_offer_details, acorn_recommend_offers or acorn_find_offers. "Reject missing IDs" is an error constraint, not usage guidance. An agent must infer the routing decision from the tool name alone.

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