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

The annotations already cover readOnly, idempotent, non-destructive, and closed-world, so the safety profile needs no restating. The description adds real behavioral context beyond them: the result is capture-based historical data, comprising a current value, a previous value, and a positional delta. It does not say what happens if the entry has no recorded captures.

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 short sentences with no filler: the first front-loads what is returned, the second carries the input provenance. Nothing could be removed without losing information.

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 one-parameter, read-only lookup with annotations covering safety, the description is nearly sufficient: it explains the returned metrics in the absence of an output schema and pins down the input source. Only edge behavior (no prior capture, unknown entryId) is left unstated.

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?

With 100% schema coverage on a single parameter, the schema already defines `entryId`, its pattern, and its provenance in `radar_search_listings`. The description repeats that same origin hint without adding format, sourcing, or validation detail, so it neither helps nor harms beyond the baseline.

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 the specific measure it returns (product position in store search: current, previous capture, and how many positions it moved), which is concrete and distinct from siblings like radar_compare_retailer_prices or radar_check_stock_outages. It never states the retrieval verb explicitly, but the resource and the returned metrics are unambiguous.

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?

It gives a useful precondition: `entryId` must come from `radar_search_listings`, which tells the agent the call has a dependency chain. It does not say when to prefer this over sibling analyses (e.g., substitute or violation tools) or what to do when no prior capture exists.

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