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

With destructiveHint=true and readOnlyHint=false in the annotations, the description adds the crucial nuance that the tool only prepares the action: 'Nothing happens yet', a confirmUrl is returned, the human must press Confirm in Netto, and the link expires in 30 minutes. It also gives an output-reporting rule ('Never say it was done'), which is exactly the behavioral context annotations cannot carry.

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?

Front-loaded with the action and scope, then the prerequisite, then the confirmation contract and the expiry. Five short sentences, each carrying distinct operational information, with no 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?

There is no output schema, and the description compensates by describing the return value (a confirmUrl) and its lifecycle. Combined with the parameter constraints and the two-step human-in-the-loop flow, an agent has everything needed to call it and report 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?

Schema coverage is 100%, so both parameters are already documented. The description adds the constraint that invoiceId must reference an open or overdue invoice, but says nothing about customerName or how it is used in the confirmation reply. Baseline 3 is appropriate given the schema does the heavy lifting.

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 ('Prepare a payment reminder email for one open or overdue invoice') with the scope constraint (single invoice, open/overdue) and escalation behavior. It also names the sibling tool that supplies the input (query_open_invoices), so it is distinguishable from send_invoice and send_quote without opening any schema.

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 where to get invoiceId ('Use invoiceId from query_open_invoices') and limits the tool to open or overdue invoices. It does not state when to prefer an alternative (e.g. send_invoice for a new invoice, or check_receipts before chasing), so the exclusion side is implied rather than spelled out.

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