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

With no annotations provided, the description carries the full burden. It discloses the role requirement, which is useful. However, it does not mention that setting 'confirm' to false returns a preview, the idempotency behavior, or any side effects on the invoice status. These are left to the schema, but the description could provide more behavioral context.

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 exceptionally concise: two sentences, no superfluous words, front-loaded with the purpose and effect. Every sentence adds value.

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 (5 parameters, no output schema, no annotations), the description is minimal. It covers the core action and role requirement but does not explain the preview mode, idempotency, or what happens to the invoice after the note is created. The schema fills some gaps, but the description could be more complete for an agent to use confidently.

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% coverage, so the baseline is 3. The description does not add any parameter-specific information beyond what the schema already provides (e.g., constraints on credit_amount, purpose of confirm flag). No extra guidance is given.

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 (create), the resource (credit note), the target (against an existing invoice), and the effect (reducing the amount owed). This distinguishes it from sibling tools like issue_invoice or void_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 provides a clear context for when to use the tool: when reducing the amount owed on an invoice. It also specifies a role requirement (Finance role or above). However, it does not explicitly contrast with alternatives like voiding or writing off, which would help the agent choose among siblings.

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