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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false. The description adds context beyond them: the concurrency token requirement and the fact that the saved record with a new SyncToken is returned. It does not elaborate on what the destructive update can overwrite, though the nested entity schema does.

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 tightly written sentences with the required inputs and return behavior front-loaded and no filler. 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?

No output schema exists, and the description covers the return value (saved record plus new SyncToken). For a mutation tool with rich annotations and a fully documented nested entity schema, this is close to complete; it omits any mention of permission or error-permission constraints.

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 entity schema deeply documents sparse semantics, SyncToken requirements, and prohibited fields. The description only restates the Id/SyncToken requirement, so it adds little beyond what the schema already provides; 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 purchase order in QuickBooks Online'), clearly distinguishing it from create_purchase_order, get_purchase_order, and delete_purchase_order by name and scope. It does not explicitly name a sibling or routing condition, so it stops just short of a 5.

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 concrete prerequisite for use: the caller needs the Id and the current SyncToken 'as the last search or write returned it,' which implicitly routes the agent through a read before updating. It does not state when to prefer this over alternatives (e.g., sparse vs full update strategy is left to the schema), but the operational context is clear.

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