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

Annotations already declare readOnly/destructive/openWorld, so the safety profile is covered. The description adds real behavioral context beyond that: ordering (newest first), the record types returned (including failed attempts), the amount unit (cents), and the auth requirement (Cotlet API key with app access). It does not discuss pagination, which the schema covers via cursor.

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?

Front-loaded and mostly efficient, but the opening sentence noticeably overlaps the second ('payments and refunds ... with amount, status and date' vs 'payments, refunds and failed attempts, with the amount in cents and the invoice'). One of the two could be dropped without losing information.

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 previews the returned fields (amount, status, date, invoice) and the auth prerequisite. It is complete enough to call correctly; only pagination behavior is left entirely to the schema.

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 all three parameters are already documented in the schema. The description adds the cents unit and the account scoping but nothing about cursor or per_page semantics, so baseline 3 is appropriate.

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 (lists the transactions of one account) and enumerates what the resource contains: payments, refunds and failed attempts. It clearly distinguishes itself from recurly_list_invoices by describing transaction-level records rather than invoices.

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?

Gives a concrete use context: 'see why an invoice is past due before you act on it.' This tells the agent when to reach for it, though it names no alternative sibling (e.g., list_invoices) or explicit when-not condition.

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