get_invoice

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

With no annotations provided, the description fully carries the behavioral disclosure burden. It explicitly states that the tool raises on unknown invoices, returns different structures per ERP system, and includes a warning about duplicate-invoice detection (the PO-8808 trap). This is rich, actionable behavior detail beyond the schema.

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 structured with a clear opening sentence, a bullet for the parameter, and then system-specific return details. Every sentence adds value, and there is no fluff. It is appropriately sized for a tool with cross-system behavior.

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?

The tool handles multiple ERP systems and has an output schema, but the description still explains key return shapes and edge cases like duplicate invoices. It also covers error behavior. For a single-invoice fetch with this complexity, the description is 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?

The input schema only provides the parameter name 'invoice_id' with no description (schema coverage 0%). The description compensates fully by explaining it is a 'corpus invoice id' and gives a concrete example ('INV-01'). This is exactly the kind of semantic addition needed.

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 starts with a specific verb+resource: 'Fetch one supplier invoice' and further clarifies it as the 'charged' leg of the match, distinguishing it from sibling tools like get_purchase_order or get_goods_receipt. It clearly states what the tool does.

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?

The description implies usage context: it fetches a single invoice by ID, supports multiple ERP systems, and is part of an invoice-PO matching workflow. It provides clear context but does not explicitly state when-not-to-use or name alternatives, so it misses the top tier by a narrow margin.

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