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

Annotations declare readOnlyHint=true, so the safety profile is already covered. The description adds value beyond that by disclosing the returned content (line items, payments applied, totals), which matters because no output schema exists. It does not cover behavior for an invalid or missing jnid.

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 compact sentences: the payload description first, the underlying endpoint second. No filler and nothing important buried.

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 single-record read with no output schema, the description usefully enumerates the returned fields and gives the backing endpoint. Only error/not-found behavior is unaddressed, a minor gap for this tool's complexity.

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?

Only one parameter and schema coverage is 100%, so the schema already fully documents jnid. The description restates 'by jnid' without adding format or lookup semantics, which is the expected baseline when the schema does the work.

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 (Fetch) plus resource (single invoice) and enumerates the returned payload (line items, payments applied, total, total_paid, due). This clearly separates it from the sibling jobnimbus_list_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?

Usage is implied by 'single invoice by jnid' versus the list sibling, and the required jnid signals when it can be called. However, it never explicitly names jobnimbus_list_invoices as the alternative for browsing, so the when-not condition must be inferred.

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