List invoices

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value beyond that: amounts are in minor currency units, filters combine with AND, and include_contact_details also stops redaction of emails, phones, NHS-shaped digit groups and postcodes — a non-obvious side effect an agent must know before setting it.

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 dense sentences, front-loaded with what the resource returns followed by filter and flag behavior. The long field enumeration is information-bearing rather than padding, though it slightly crowds out the filtering guidance.

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?

With no output schema, the description usefully enumerates the returned fields and units, and covers the filtering and redaction behavior an agent needs. Pagination via cursor/max_results is left entirely to the schema, which is acceptable but slightly thin for a paginated list tool.

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?

With 60% schema coverage, the description compensates by documenting three of five parameters and adding semantics the schema lacks: booking_id and patient_id are ANDed, and include_contact_details gates the payment link. It adds nothing for cursor/max_results, but those are already explained in the schema.

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 the resource (invoices in the Organization) with a specific enumeration of the returned fields (status, totals, outstanding/paid amounts, supply date, payor type, ids, line items). It is clearly distinguishable from get_invoice and list_payments by naming what the list returns and which filters apply. It does not explicitly say 'list all' but the plural resource plus filters makes the verb unambiguous.

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 tells the agent that booking_id and patient_id are ANDed and that the Patient Portal payment link requires include_contact_details, which is actionable usage context. However, it never says when to prefer this tool over get_invoice (single invoice) or list_payments, so routing guidance is implied rather than explicit.

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