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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is low. The description adds genuine behavioral value by disclosing the full outcome space (pending, completed, declined, expired) and noting that a completed request carries an acquired_copy_id, which the annotations cannot convey.

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?

One dense sentence, front-loaded with the resource and its outcome states, with the follow-up action packed into a parenthetical. No filler or repetition.

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 its job by enumerating the returnable status values and the one meaningful payload field (acquired_copy_id). It omits where the purchase_request_id originates and any polling/expiry semantics, which keeps it just short of fully self-contained.

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 description coverage is 0% and the single parameter is required, so the description must carry the burden. It conveys the id's provenance ('a purchase you requested') but adds no format or shape detail beyond the pattern already present in the schema, leaving it only partially compensating.

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 states the exact resource returned (the status of a previously requested purchase) and enumerates the four possible outcomes, which lets an agent distinguish it from the sibling request_purchase that initiates a purchase. It stops short of explicitly naming the initiating/alternative tool, so differentiation is implied rather than spelled out.

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 clear operational context: call this to check on a purchase you already requested, and when the result is 'completed' use the acquired_copy_id with fetch_session_context. It names the follow-up sibling and the condition that triggers it, though it never states outright when to prefer this over request_purchase or how often to poll.

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