get_invoice

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

The readOnlyHint annotation already signals this is a safe read operation, so the description doesn't need to repeat that. The description adds 'full details' as return context but does not disclose behavior for missing IDs, permissions, or response structure. This is adequate for a simple read tool.

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 a single, front-loaded sentence with no filler. Every word contributes to the tool's purpose and usage.

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 lookup with one parameter and a readOnlyHint annotation, the description is largely complete. 'Full details' implies the response contains comprehensive invoice information. It could be slightly improved by noting not-found behavior, but nothing essential is missing for selecting and invoking the tool.

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%, so the description bears the burden of explaining the parameter. The phrase 'by ID' clarifies that invoiceId is the invoice identifier, but it adds no detail about value format, requiredness, or error conditions. The single obvious parameter makes this minimally sufficient.

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 clear verb ('Get'), a specific resource ('full details for a single invoice'), and the key identifying scope ('by ID'). It is immediately distinguishable from plural list siblings like get_invoices and get_customer_invoices.

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 clearly implies usage when a specific invoice ID is known and the agent needs one invoice's complete data. It doesn't explicitly name alternatives like get_invoices for listing, but the singular 'by ID' phrasing provides enough contextual direction.

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