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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds useful domain context about multicurrency, but it does not describe edge behavior such as an invalid Id or what happens when multicurrency is disabled. This is acceptable given the read-only annotation, but not richly transparent.

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 short sentences with no filler. The primary action is front-loaded, and the domain clarification about multicurrency earns its place by preventing misuse in non-multicurrency companies.

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 simple get-by-id tool with two parameters and no nested objects, the description plus schema is sufficient for correct invocation. The lack of an output schema means return-value details are not described, but the resource semantics and identification-by-Id are clear enough.

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%, with both 'id' and 'company' clearly described in the input schema. The description adds minimal parameter-level meaning beyond restating lookup 'by Id,' so it meets the baseline for high schema coverage but does not elevate it.

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: 'Get a single company currency from QuickBooks Online by Id.' It also distinguishes itself from sibling search tools by emphasizing 'single' and lookup by Id, so an agent can tell it apart from search_company_currencies without opening the schema.

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 description gives clear context for when the tool is relevant: CompanyCurrency is 'the currencies the company transacts in' and is 'only meaningful with multicurrency enabled.' It does not explicitly name alternatives like search_company_currencies, but the 'single ... by Id' phrasing implies the line between direct lookup and search.

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