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

No annotations are supplied, so the description carries the full behavioral burden. It implies a non-mutating status check and hints that the result is a consumed/not-consumed determination, but stays silent on permissions, behavior for unknown payment_id or malformed tx_hash, rate limits, and the exact response shape.

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 sentence, front-loaded with the recovery scenario, then the exact semantic of the call after the colon. Nothing is redundant and every clause carries 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 two-parameter lookup with no output schema, the description covers the essential intent check (was this payment already consumed) and the reason to call it. Remaining gaps are the return-value shape and failure modes for invalid or unknown identifiers, which matter more here because no output schema exists.

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%, so the description must compensate and largely does not. It correctly conveys that both values are used together as an identifying pair, but never says where the agent obtains payment_id or tx_hash (e.g., from the original prepare_purchase call) or how they are validated beyond the regex and length constraints the schema already encodes.

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 gives a concrete operation on a concrete resource: it reports whether a specific (payment_id, tx_hash) pair has already been consumed. That distinguishes it from the write-oriented siblings complete_purchase and prepare_purchase, though the opening phrase 'Recover a purchase' overstates the capability, since the tool only reports status rather than performing recovery.

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 trigger condition is explicit: use this after a dropped connection to determine whether a purchase already went through. No sibling is named as an alternative and no when-not-to-use case is given, but the recovery scenario is strong enough to route an agent correctly in the ambiguous-retry situation.

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