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

Annotations already signal a destructive write (destructiveHint=true, readOnlyHint=false), and the description's 'Update' is consistent with that. The description adds the Id/SyncToken precondition but does not surface the sparse-by-default, full-update, or retire-via-Active:false behaviors in the tool description itself; those are documented in the entity parameter schema.

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 description is a single front-loaded sentence that names the action, target, and prerequisite without filler or repetition of the title. Every word earns its place.

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?

The terse tool description is supported by a rich entity parameter schema and clear annotations, giving the agent the key invocation details: required fields, sparse/full-update behavior, sensitive-field restrictions, and company selection. The main gap is the lack of any response-format guidance, but there is no output schema to lean on.

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 property already details Id/SyncToken requirements, sensitive-data exclusions, sparse updates, line-array replacement, and Active:false retirement. The tool description's parenthetical only restates the Id/SyncToken requirement and adds no new parameter-level meaning, so the baseline score is appropriate.

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 concrete action ('Update') on a specific resource ('an existing item') in QuickBooks Online, with a clear prerequisite requiring Id and SyncToken. This makes the intent unambiguous and distinguishes it from creating a new item, though it does not explicitly contrast with sibling update_* tools.

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 phrase 'existing item' and the Id/SyncToken requirement imply this is for modifying an already-created item rather than creating a new one. However, it does not explicitly name alternatives like create_item, nor does it state when not to use the tool or that the item should be fetched first.

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