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

Annotations already declare destructiveHint=true and idempotentHint=true, so the agent knows this mutates state and is repeatable. The description adds nothing beyond that — it doesn't say what is destroyed or overwritten, whether an existing PO link is replaced, or whether the action can be undone.

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 front-loaded sentence with no filler. It is appropriately sized, though its brevity reflects under-specification rather than disciplined editing.

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, non-readonly mutation with 0% parameter documentation and no output schema, the description is too thin: it omits what linking changes, side effects, and any preconditions the agent should check.

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% for both parameters, so the description must compensate. It only loosely maps the two args ('invoice' -> invoice_id, 'purchase order number' -> po_number) and gives no format, ID-space, or validation detail for either.

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 ('Link') and both resources ('invoice', 'purchase order number'), which is clear enough to distinguish from siblings like approve_invoice or match_bank_transaction. It does not, however, contrast itself with any sibling or clarify what 'link' means operationally.

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 when-to-use guidance, no prerequisites (e.g., invoice must exist or be unlinked), and no mention of alternatives despite a dense sibling set. The agent must infer everything from the tool name.

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