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

The description adds substantial behavior beyond the annotations: the tool only queues a pending change, requires human approval via approvalUrl, never touches Xero itself, and produces a Xero-side DRAFT. This richly supplements readOnlyHint=false, openWorldHint=true, idempotentHint=false, with no contradiction.

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 front-loaded with the core purpose and contains valuable details, but it is somewhat repetitive around the theme of not touching Xero ('does NOT touch Xero itself', 'before Xero is touched at all', 'never posts anything itself'). Still, every sentence 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?

For a tool with no output schema, the description is remarkably complete: it covers geographic restrictions, the approval workflow, the approvalUrl field, the eventual DRAFT state, and the separation from post_xero_pay_run. An agent has everything needed to invoke it correctly.

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 coverage is 100%, but the description adds meaningful context by explaining that payrollCalendarId must be sourced from list_xero_payroll_employees and never invented, and why period start/end and payment date parameters are absent. The organisation parameter's optionality is also clarified.

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 action ('Proposes a DRAFT pay run for one payroll calendar'), a geographic scope, and explicitly contrasts itself with post_xero_pay_run. It is unambiguous about what the tool does and does not do, making it easy to distinguish from 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?

It gives explicit when-to-use guidance: Australian or New Zealand organisations, not the United Kingdom, and not as a posting step. It names post_xero_pay_run as the irreversible final step and even references list_xero_payroll_employees as the source for payrollCalendarId.

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