get_invoice

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

Annotations provide readOnlyHint=true and the description ('Get') is consistent, so there is no contradiction. The description adds output-content context (billing breakdown categories) but does not disclose behavioral details such as error conditions, data scope, or response structure; given the read-only annotation, 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?

One sentence that front-loads the primary action and resource, then adds relevant detail about the breakdown. There is no filler or redundancy.

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-parameter read-only lookup with no output schema, the description is mostly sufficient: it names the resource, selection key, and return-value highlights. It could be stronger by referencing list_invoices as the discovery path, but nothing essential is missing for 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?

The input schema fully documents invoiceId as an integer with description 'Invoice ID' (100% coverage), so the schema carries the parameter semantics. The description's 'by ID' simply reuses that concept without adding format, source, or constraints.

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 ('Get'), a concrete resource ('specific invoice'), and identifier-based selection ('by ID'), which clearly separates it from listing tools like list_invoices. It also previews the expected content ('full billing breakdown including storage, API calls, egress, and ingress costs'), making the tool's function unambiguous.

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?

There is no explicit guidance about when to prefer this tool over siblings such as list_invoices or get_usage. The phrasing 'specific invoice by ID' implies it is for fetching one known invoice, but the description does not name alternatives or state exclusions.

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