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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description earns credit by disclosing a genuine output quirk not visible anywhere else: amounts are bare numbers carrying no currency, which changes how an agent must present results.

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 tight sentences: the first defines the payload, the second front-loads the failure mode (currencyless amounts) and the fix. Nothing is redundant with the title or annotations.

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?

With no output schema, the description must describe the return shape, and it does by naming the key fields, plus it flags the currency caveat that would otherwise cause a silent error. For a single-parameter read tool this is sufficient.

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?

There is a single parameter (id) and schema description coverage is 100%, so the schema already carries the semantics. The description adds nothing about the identifier's form or origin. Baseline 3 applies 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 and resource (Get invoice) and enumerates the payload contents (amounts, dates, linked vendor, project, purchase order), which lets an agent confirm it returns the full record rather than a summary. It is distinguishable from list_invoices, which returns collections.

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 supplies a concrete cross-tool rule: call get_organization_settings for currency_code before stating an amount. That is prescriptive guidance for correct use. It does not, however, state when to reach for get_invoice over list_invoices, so it stops short of full when/when-not coverage.

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