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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the optimistic-concurrency requirement (current SyncToken) and the fact that the saved record along with a new SyncToken is returned, which matters since no output schema exists. It stops short of describing what 'destructive' actually means in sparse-update terms, which the schema covers instead.

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 tight sentences: the action and its required preconditions come first, the return value second. No filler and nothing repeated for padding.

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 correctly compensates by stating what is returned (the saved record with its new SyncToken). Combined with a fully documented schema and destructive/readOnly annotations, an agent has what it needs to invoke this safely, with only the sparse-vs-full update behavior left entirely to the schema.

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 100%, and the nested entity object already documents Id, SyncToken, sparse-vs-full update semantics, and the Line array replacement rule. The description restates the Id/SyncToken requirement, which reinforces but does not extend the schema, so the 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?

The description states a specific verb and resource ('Update an existing sales receipt in QuickBooks Online'), naming the domain and the target entity precisely. It does not explicitly differentiate itself from the adjacent siblings (update_refund_receipt, create_sales_receipt, void_sales_receipt, delete_sales_receipt), but the verb+resource pairing is unambiguous enough that an agent could pick it correctly.

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 an implied precondition ('requires Id and the current SyncToken, as the last search or write returned it'), which effectively routes the agent to a prior search or write. However, there is no explicit when-to-use vs. when-not guidance, and no statement of when to prefer void_sales_receipt or the delete/update siblings instead.

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