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

Annotations already declare the write/safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), so the bar is lower, and the description adds genuinely useful state-machine context: the operation only succeeds on a draft and is refused post-approval. It does not mention permissions/auth or what happens to the previous description text, so it stops short of full disclosure.

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 sentences, each earning its place: what it does, the state constraint, and the routing to the alternative tool. The key constraint (draft-only) is front-loaded in the first sentence.

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?

An output schema exists, so return values need not be described, and annotations carry the safety profile. The description covers scope, precondition, exclusion, and fallback tool, which is close to complete for a mutation of this size, with the only real gap being parameter-level detail on invoiceId/lineId/description.

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 schema only carries a minLength/maxLength on description; nothing documents the invoiceId/lineId pairing (lineId even $refs invoiceId). The description says a 'line description' is being corrected but adds no format, length, or identifier semantics, so it does not compensate for the documentation gap across three required parameters.

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?

The description states a specific verb+resource ('Correct a line description') and scopes it to a draft invoice, which is far more than a restatement of the name. It also explicitly names a sibling for the adjacent case (suggest_invoice_change with add_line), so an agent can distinguish it from the other line-oriented tools without opening schemas.

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?

It gives an explicit precondition (invoice must still be a draft), an explicit exclusion (a different description is refused after approval), and a named alternative for the case where you want a different line (suggest_invoice_change with add_line). Nothing about when to pick this tool is left to inference.

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