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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the description focuses on what matters: failing checks cite the enforced clause, and the response itself carries a disclaimer that verdicts are readiness signals, not legal determinations. That interpretive framing is genuine value beyond annotations, though nothing is said about response size, latency, or behavior for unknown unit ids.

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?

Front-loaded with what the tool returns, then the questions it answers, then the caveat — a sensible ordering. The closing disclaimer is slightly redundant ("verdicts are readiness signals... and the response says so" followed by "Never report one as confirmation"), but the repetition is defensible for a legally loaded output.

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 burden of explaining returns, and it does: custody hops, tamper status, regulation verdicts, and clause citations for failures. Only minor gaps remain — nothing about error behavior or result volume for a potentially long append-only log.

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%, so both unit_id and pack are already documented, including the note to use find_unit when only a scan is available. The description only loosely gestures at pack via "what each regulation makes of it" and adds no syntax or defaulting detail beyond the schema, so 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 resource and scope: the full custody history of one serialized unit, its tamper check, and per-regulation verdicts. This clearly separates it from siblings like where_is (point location), chain_readiness (aggregate), and find_unit (lookup), so an agent can pick it without opening the 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 concrete triggering questions ("where has this been", "who handled it", "is its record trustworthy", "does it pass DSCSA / EU passport") that map directly to use cases. It does not name exclusions or alternatives — notably where_is for a quick current location — so the boundary with that sibling is left to inference.

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