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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description still adds behavioral value: 'Deterministic' signals reproducibly identical output for the same id, which is stronger than idempotency alone, and 'one per domain' sets the result shape. It omits failure behavior for unknown ids, so it is not fully exhaustive.

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?

Three short sentences, zero filler, front-loaded with the core action and scope before the tooling prerequisite. Every sentence 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?

With no output schema, the description carries the return-shape burden and does it: one structural twin per other domain. Annotations cover the safety profile. Only the unknown-id / empty-result behavior is left unspecified, a minor gap for a deterministic read tool.

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%: the id format (eng_.../soc_...) and the limit cap ('Max cross-domain analogs, one per domain') are already documented in the schema. The description's 'in each OTHER domain' reinforces the limit semantics slightly but adds no syntax or format detail beyond it, 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 ('find its closest structural twin') and a precise scope ('in each OTHER domain'), with the gloss 'same structure, different domain' that immediately separates it from a same-domain relatedness tool. An agent can distinguish this from coldstate_related without opening either schema.

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?

Gives an explicit prerequisite ('Use coldstate_resolve to turn a name into an id first') so the agent knows how to obtain the required id. It implicitly distinguishes itself from same-domain siblings via 'each OTHER domain' but never names an alternative or a when-not condition, so it stops short of the top band.

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