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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, not open-world), so the description earns credit for what it adds: snapshots are written as a side effect of inventory lookups, the result is capped at 400 and sorted newest first, and empty results are explained. It does not describe rate limits or response envelope shape beyond `totals`.

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?

The lead sentence is well front-loaded, but the definition of `totals` — 'each of those days' total value in cents (that day's holdings at that day's prices)' — is stated twice almost verbatim, and the text wraps awkwardly mid-clause. A third of the length could be removed with no loss.

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 does the work of documenting the return (list of dates plus per-day totals in cents, newest first, capped at 400), which is what an agent needs. The duplication is waste rather than a gap; only edge-case behavior for zero snapshots is left implicit.

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?

There is a single parameter, steamid, with 100% schema description coverage (17-digit SteamID64), so the schema already carries the semantics. The description adds nothing parameter-specific; its added meaning is about the returned `totals`, not the input. 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 — the dates on which a daily snapshot of this inventory was stored — with ordering (newest first) and a cap (up to 400), plus the `totals` payload. It also distinguishes itself from the sibling that fetches a single day's snapshot by naming that endpoint (/inventory/{steamid}/snapshots/{date}, i.e. get_inventory_snapshot).

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?

Explains the precondition that makes results non-empty (only inventories someone has looked up have snapshots) and routes to the companion call for a single day's data. It also states 'No key needed,' removing an auth question. No explicit when-not-to-use versus get_inventory_value_history, which keeps it below a 5.

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