Update a recurring invoice

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

Annotations already declare readOnlyHint=false and idempotentHint=true, so the safety profile is covered, but the description adds no extra behavioral context such as whether the update is a full replacement, what happens to existing fields, or any side effects. The only hint is the PUT method in the endpoint line, which is not expanded.

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 short and front-loaded with the core purpose, but it redundantly repeats 'Update a recurring invoice' in the first two sentences. The endpoint line is useful context, but the repetition wastes space.

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?

Given the complexity of the RecurringInvoiceInput with nested subscription and line objects, the description is minimal. It does not explain how updates behave (e.g., whether omitted fields are reset, how to preserve attachments), which is important for a PUT operation. The schema partially compensates, but the description leaves key decisions to inference.

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?

The schema's description coverage is 67% and the parameter definitions are detailed (e.g., attachments note, subscription fields). The tool description itself adds no parameter-specific meaning, so it stays at the baseline since the schema does the heavy lifting.

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 clearly states the action 'Update' with a specific resource ('recurring invoice') and identifies 'by ID', making it unambiguous. It inherently distinguishes from sibling tools like create_recurring_invoice.

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 is implied that this tool is used when you need to modify an existing recurring invoice, and the tool name itself contrasts with create_recurring_invoice. However, there is no explicit guidance on when to prefer this over alternatives or what conditions must be met (e.g., the invoice must already exist).

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