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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuine value by disclosing that the response is a composite object including line items, payments and delivery, which matters for a single-fetch with no output schema.

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 short sentences with the payload description front-loaded and no filler. The trailing endpoint reference is mildly redundant but inexpensive and aids orientation.

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 one-parameter read tool with full annotation coverage and no output schema, the description covers enough: identity, what comes back, and the backing endpoint. The only meaningful gap is not routing the agent between id-based and code-based lookups.

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 coverage is 100% and there is only one parameter (invoice_id, described as 'KiotViet invoice id'), so the schema does the work. The description's 'by id' adds nothing beyond it — no format, validity, or not-found behavior.

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: retrieve a single invoice by id, and names the payload it returns (lines, payments, delivery). This clearly distinguishes it from kiotviet_list_invoices, though it never explicitly distinguishes it from the sibling kiotviet_get_invoice_by_code.

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 only implied by 'by id' — the agent can infer this is the id-based lookup, but the description never says when to prefer it over kiotviet_get_invoice_by_code or list_invoices. No exclusions or prerequisites are stated.

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