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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description is consistent with them. It adds genuinely useful context beyond the annotations: an exact preview plus a five-minute confirmation token, and the warning that financial changes can reset approval. It stops short of describing what happens after token expiry or how the token is consumed.

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?

Three short clauses, zero waste, and the two most consequential facts (requires confirmation, does not apply) are front-loaded ahead of the return-value details.

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?

With no output schema, the description usefully explains what comes back (an exact preview and a five-minute confirmation token). The main remaining gap is the semantics of the nested edit fields and what the caller does with the token, but annotations already cover the safety profile, so this is close to complete.

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% and the single parameter wraps a nested object with six editable fields, none of which are documented. The description adds no field-level meaning, such as whether null clears a value or whether omitted fields stay unchanged — behavior an agent must get right before previewing a financial edit.

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 action (prepare/preview changes to a single previously read invoice line) and immediately contrasts it with the mutation it precedes: 'it does not apply the change.' This cleanly separates it from the sibling edit_invoice_line_item without requiring the schema to be opened.

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?

'Requires confirmation' plus 'does not apply the change' implies the preview-then-apply workflow, and 'previously read invoice line' implies get_invoice_line_items must run first. It never names the sibling to call next or states what to do when the token expires, so the routing is inferred rather than explicit.

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