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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered structurally. The description adds no behavioral context of its own — nothing about error behavior for an unknown id, tenant scoping, or what a miss looks like — so it is merely non-contradictory rather than informative.

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 short sentence with zero filler and the essential information front-loaded. It is efficient, though its brevity is close to under-specification rather than deliberate compression.

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 lookup with a fully documented schema, this is just barely enough to invoke correctly. There is no output schema, and the description says nothing about the returned shape or failure mode, leaving a modest gap an agent must discover empirically.

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 100% with a single parameter whose meaning ('The invoice_item id.') is fully documented in the schema. The description's 'by id' restates that without adding format, source, or scoping details, so the baseline 3 applies.

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?

A specific verb (read) plus a specific resource (one invoice_item) qualified by lookup key (id) — an agent knows immediately what this does. It does not, however, distinguish itself from the many nearby siblings such as invoice_item_list, quote_item_read, or invoice_read.

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 guidance on when to use this versus invoice_item_list or invoice_read, nor any mention that an id must be obtained first. The 'by id' phrasing weakly implies the precondition, but nothing is stated explicitly.

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