get_invoice

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is fully covered by structured data. The description adds nothing beyond that: no error behavior for a missing invoice, no auth/scope requirement, no rate-limit or caching context. It simply restates the read.

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?

One sentence, no filler, with the resource and lookup key front-loaded. Nothing can be trimmed without losing 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?

An output schema exists, so return values need not be described, and annotations cover the safety profile. What remains missing for a lookup tool is failure behavior (invoice not found, unauthorized) and any routing hint toward list_invoices, leaving the definition adequate but thin.

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?

Schema description coverage is 0% for the single parameter, so the description must carry the load. 'By invoice number' does clarify that invoice_id is the human-facing invoice number rather than an internal surrogate key, which is a small but real gain over the schema's bare 'Invoice Id'. It gives no format, range, or example beyond the schema's exclusiveMinimum constraint.

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?

States a specific verb and resource ('Get a single account invoice') and the lookup key ('by invoice number'). The word 'single' implicitly separates it from the sibling list_invoices, but the description never names that alternative explicitly, so it stops short of full sibling differentiation.

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?

Usage is only implied: an agent can infer this is the tool to use when it already holds one invoice identifier, versus list_invoices for browsing. There is no explicit when-to-use, when-not-to-use, or prerequisite (e.g. permission scope) stated.

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