Get invoice

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds value by stating what the response includes (line items, totals, payment status), but it does not disclose error behavior, authorization nuances, or whether the invoice data is fully hydrated. This is adequate but not rich.

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, no filler. The core action and return contents are front-loaded, and the alternative-tool guidance is placed in the second sentence without unnecessary elaboration.

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 read-only getter with fully documented parameters and safe annotations, the description covers the essential return contents and points to the PDF sibling. It does not describe error cases or the full invoice object shape, but with no output schema and a straightforward operation, the description is sufficiently complete for correct invocation.

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 100%, so the schema already documents both parameters thoroughly. The description reinforces that lookup is by id but adds no new parameter-level meaning beyond what the schema provides. Baseline 3 is appropriate.

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 verb and resource ('Get one invoice by id') and enumerates the key returned data (line items, totals, payment status). It also distinguishes itself from ws_invoice_pdf by clarifying that the PDF is a separate tool, so an agent can select this tool correctly without ambiguity.

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 names the alternative tool for a related but different need: 'Use ws_invoice_pdf for the document itself.' This provides clear routing guidance and prevents an agent from using this tool when the actual goal is to obtain the PDF document.

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