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

Annotations already declare destructive=true, idempotent=true, and readOnly=false, so the safety profile is covered. The description adds valuable workflow context: token-only invocation, confirmation gating, expiry behavior, and that a correction is recorded. It does not explain what a 'correction' record contains, but the annotations carry much of the remaining burden.

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?

The description is front-loaded with the critical constraint and is only a few sentences long. A little repetition exists around confirmation, but each sentence carries relevant guidance.

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 destructive, preview-gated mutation with no output schema, the description covers the workflow, required token semantics, expiry behavior, and confirmation requirement. An agent has enough context to invoke it correctly.

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?

With only one parameter and reported schema description coverage of 0%, the description compensates by clarifying that the sole accepted input is the confirmation_token and that it must come from this tool's own preview and user confirmation. This adds practical meaning beyond the raw schema reference.

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 ('add_invoice_line_item') and explicitly ties it to the preview workflow, so the agent can distinguish it from preview_add_invoice_line_item, edit_invoice_line_item, and remove_invoice_line_item. The scope 'one explicit new invoice line' is clear.

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?

Explicitly says to use this only after 'preview_add_invoice_line_item' and user confirmation, and warns that changed or expired records need a new preview. This names both the prerequisite tool and the condition under which it must not be used.

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