Invalidate Purchase Invoice

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

Annotations already establish readOnly=false, destructive=false and idempotent=true, so the safety profile is covered. The description adds genuinely new context: this is a reversible, non-destructive correction path and carries an RPS § 10 traceability obligation. It does not, however, describe side effects on linked documents or whether re-confirmation is required.

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 short sentences, front-loaded with the state transition and followed by the compliance note. No filler, no redundancy; every clause carries 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?

For a single-parameter tool with annotations covering safety, the description covers the main effect. However, it omits what the caller gets back and whether the invoice must be re-confirmed, and the instruction to 'record why and what replaces it' is not achievable through the schema, which exposes only an integer id — leaving that requirement unactionable.

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?

There is a single parameter with 100% schema description coverage, so the schema already documents the id field. The description adds no syntax, format, or acceptance constraints for that id, making the baseline of 3 correct.

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 gives a specific verb and resource (invalidate → purchase invoice) and, unusually for an 'invalidate' tool, states the concrete effect: moving a confirmed invoice back to draft for editing. That implicitly separates it from delete_purchase_invoice and update_purchase_invoice, but it never names those siblings explicitly, so it falls short of a 5.

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?

'...to draft status for editing' implies the use case (edit a confirmed invoice), but the description never states when to choose this over delete_purchase_invoice or update_purchase_invoice, nor any precondition such as the invoice being confirmed first. Usage is inferable rather than stated.

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