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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the agent knows this is a mutating operation. The description adds no behavioral details beyond 'create' – no mention of required permissions, side effects, or what happens on success/failure. The entity parameter description does add a useful constraint (do not send government identifiers, birth dates, card-processing details), which is a behavioral guardrail. However, the core description itself is minimal.

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, clear sentence that front-loads the core purpose. It is appropriately concise. The schema's entity description is longer but earns its place by providing critical data-handling constraints. No fluff or redundancy.

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 operation with a nested object parameter and no output schema, the description is adequate but not rich. It tells the agent what to create and warns about sensitive fields, but doesn't describe the expected response, error conditions, or any prerequisites (e.g., customer must exist). Given the complexity of a QuickBooks Invoice object, more guidance on required sub-fields or common pitfalls would improve completeness.

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%, so the schema already documents both parameters. The entity parameter description adds meaningful guidance beyond the schema: it explicitly warns against sending sensitive data (SSN, tax IDs, birth dates, card-processing details) and directs managing those fields in QuickBooks. The company parameter is also clearly explained. This exceeds the baseline 3 for full coverage.

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: 'Create an invoice in QuickBooks Online.' This clearly identifies the operation and target system. It doesn't explicitly differentiate from sibling tools like create_credit_memo or create_sales_receipt, but the resource 'invoice' is distinct enough among the create_* siblings.

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 implies usage: use this when you need to create an invoice in QuickBooks. It doesn't explicitly state when not to use it or mention alternatives like create_sales_receipt or create_credit_memo. The schema's entity description adds some context about what to send, but no explicit routing guidance is provided.

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