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

Annotations only cover the safety profile; the description adds substantial behavior beyond that: the purchase appears with status 'Te controleren', recognition is imperfect, it stays on Vraagposten until a cost account is set, nothing is booked final, and a Cotlet API key with access is required. This is exactly the operational context an agent needs.

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?

Purpose is front-loaded and most sentences carry real information. It runs slightly long and the 'reaches no one and books nothing final' sentence is a bit conversational, but nothing is filler.

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 2-parameter upload tool with no output schema, the description fully covers what the file becomes, the recognition caveats, the pending state, and the auth requirement. Nothing needed to call it correctly is missing.

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 coverage is 100%, so the schema already documents both parameters including accepted extensions and base64 encoding. The description repeats the accepted formats but adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 precise verb and resource ('Uploads one PDF, UBL, PNG or JPG file to Inkopen for SnelStart to read') and clarifies the intent by analogy ('Does what dragging a file into Inkopen does'). This is easily distinguished from the many create/list sales-invoice siblings.

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?

Gives clear context: it's for purchase invoices/receipts destined for Inkopen recognition, and it explicitly notes that no confirmation is prompted because nothing is finalized. It does not name alternatives or exclusions, but the scoping is unambiguous.

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