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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's value-add is disclosing that the response embeds a rendered HTML document under `customers_invoice_html` — non-trivial payload information since no output schema exists. It does not clarify behavior when neither identifier is supplied.

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?

A single economical sentence with the read marker and resource scope front-loaded and no filler. Every clause (identifiers, return field) carries information.

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?

Covers what is fetched and where the HTML lands, which is what an agent needs at minimum. But with 0% schema coverage, zero required parameters, and no output schema, the silent 'no identifier supplied' case is an unresolved ambiguity the description should have closed.

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 description coverage is 0%, so the description must compensate; it names both `invoice_id` and `invoice_uuid` and signals they are interchangeable ('or'), which is real added meaning. It does not say which to prefer, whether both may be passed, or what happens if both are null (neither is required).

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 one invoice) and even names the returned field `customers_invoice_html`. The word 'One' implicitly distinguishes it from list_customer_invoices, but no sibling is named explicitly.

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 '[read]' tag and 'One invoice' hint at a single-record read, but there is no explicit when-to-use guidance, no mention of list_customer_invoices for enumeration, and no pointer to send_customer_invoice or set_customer_invoice_status for the other invoice operations.

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