delete_invoice

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

Annotations already mark it as destructive (destructiveHint: true) and writable (readOnlyHint: false). The description confirms deletion and adds that it returns 'meta.deletedRecords', which is beyond annotations. However, it doesn't disclose any additional side effects or prerequisites beyond 'drafts only', which is already covered. Still, it adds value, so 4 is appropriate.

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 sentences, no filler. First sentence front-loads the action and key constraint. Second sentence states return value. Every word is essential.

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 simple deletion tool with two well-described parameters and annotations, the description covers purpose, usage guidelines, constraints, and return value. No output schema exists, but the return info is provided. The description is fully adequate given the tool's complexity.

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 input schema has 100% description coverage for both parameters (id and verbose), so the schema already provides meaning. The description does not add new parameter details; it only reinforces that id must be a draft invoice. Baseline 3 is justified.

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 'Delete a Billy invoice', specifies the resource type, and adds a critical constraint 'drafts only'. It distinguishes from voiding/crediting approved invoices, making the purpose unambiguous and differentiated from sibling tools like approve_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?

The description explicitly states when NOT to use ('approved invoices must be voided/credited instead') and suggests alternatives ('voided/credited'), providing clear usage boundaries. This helps the AI agent decide between this tool and others like void_daybook_transaction or create_invoice (for credit notes).

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