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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the bar is lower. The description goes beyond them by disclosing the return payload ('the saved record with its SyncToken'), which matters because the SyncToken is needed for subsequent updates, and by repeating the multicurrency prerequisite.

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?

Three short sentences with the core action front-loaded and no filler. The middle sentence is a fragment ('The currencies the company transacts in; only meaningful with multicurrency enabled'), which is slightly awkward but costs no real clarity.

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 create tool with annotations covering safety, a fully described schema, and no output schema, the description is nearly complete: action, prerequisite, and return shape are all present. It could have noted required fields inside the free-form entity object or typical validation failures, but nothing essential is missing.

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 already documents the QBO object, the Code field as ISO 4217, the multicurrency requirement, and the PII fields to omit. The description adds nothing parameter-specific beyond that, 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?

States a specific verb and resource ('Create a company currency in QuickBooks Online'), which cleanly separates it from update_company_currency, delete_company_currency and search_company_currencies. It does not name a sibling explicitly, but the create/read/update/delete split is unambiguous from the verb.

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 supplies one real precondition — 'only meaningful with multicurrency enabled' — which is genuine usage context. However it gives no when-not guidance and never points to update_company_currency or search_company_currencies as the alternative when the currency already exists.

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