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

Annotations already declare readOnly/ idempotent / non-destructive, so safety is covered; the description goes further by disclosing the shape of the answer (places plus how each place is known) and an important edge case: units with no recorded place are counted and listed but never placed. It stops short of noting result limits or pagination.

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 tight sentences, front-loaded with the core behavior and the unplaced-units caveat, then the input rule. Nothing is redundant with the title or schema.

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 read-only, non-destructive lookup with no output schema, the description covers return content, the null-place edge case, and the expected identifying input. Minor gaps remain around result size/pagination and the full meaning of 'how the place is known,' but nothing blocking for correct invocation.

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 the baseline is 3, but the description adds a meaningful constraint the schema cannot express: although neither product nor lot is formally required, the caller should give product, lot, or both. It does omit any mention of the optional status filter, leaving that to the schema.

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 query: locating a product's or lot's units by last known place, enumerating the place categories (sites, partners, scans, in-transit shipments) it covers. That is far more concrete than the title, but it never names or distinguishes itself from nearby siblings like find_unit, trace_unit, or shipment_status.

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?

The closing sentence tells the agent what to supply (product, lot, or both), which implies invocation conditions. However, there is no explicit guidance on when to choose this over find_unit/trace_unit/shipment_status, nor any stated exclusions or prerequisites.

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