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

With no annotations, the description carries the burden and does well: it discloses that this is a formal submission with per-invoice billing, requires App Key, and produces invoice number and delivery info. It stops short of covering irreversibility, failure handling, or what happens if the draft is already confirmed, but the key side-effects are present.

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?

A single dense sentence opens with a step marker, then gives the required input, side-effect, prerequisite, and outcome. There is no filler or redundant restatement.

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 two-parameter tool with no output schema, the description provides enough to invoke correctly: required input, prerequisite, billing consequence, and generated artifacts. It does not describe error semantics or response format, but given the tool's simplicity and lack of output schema, this is a minor gap.

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 already documents both parameters at 100% coverage. The description adds value by specifying that draft_id is exactly the value returned by invoice_create_draft, linking the two tools in the workflow. It does not elaborate on payer_email's delivery behavior, but the schema covers it.

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 states a specific action ('confirm issuing draft') on a specific resource (the draft created by invoice_create_draft), and explicitly frames it as 'Step 2' in a workflow. This clearly differentiates it from the sibling invoice_create_draft (which creates) and invoice_query (which reads).

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 tells the agent exactly when to use it: after invoice_create_draft, passing that tool's returned draft_id. It also lists a prerequisite (App Key) and cost model. It does not, however, explicitly state when to prefer invoice_query or invoice_create_draft instead.

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