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

readOnlyHint=true already covers the safety profile, and the description adds real value by enumerating the response payload (line items, taxes, discounts, payments, totals, amount due), which matters since no output schema exists. It does not cover failure modes (e.g. invalid or unknown invoice id), keeping it short of a 5.

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, front-loaded with the action and its payload, with zero redundant wording. The endpoint reference is the only extra and is genuinely useful for cross-referencing.

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-param, read-only fetcher the definition is nearly complete: it names the resource, the identifier, and the fields returned, compensating for the absent output schema. Only error/edge-case behavior is unaddressed.

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 with 100% schema description coverage, so the schema fully documents invoice_id. The description adds no syntax, format, or lookup guidance beyond what the schema already states, which is the expected baseline.

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 ('Fetch one invoice') and lists the salient contents (line items, taxes, payments, totals, amount due), which sets it apart from the plural sibling intakeq_list_invoices without naming it. The REST mapping (GET /invoices/{id}) reinforces the single-resource scope.

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 singular 'one invoice' implies this is for retrieving a known id, contrasted with intakeq_list_invoices, but no explicit when-to-use, prerequisites, or error conditions are given. Usage is inferable rather than stated.

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