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

Annotations only declare readOnlyHint=false, destructiveHint=false, openWorldHint=true; the description adds real behavioral context beyond that: accounts are re-checked against the MF white list for today, unsafe lines are silently omitted, and the file is not transmitted to a bank. The security note about never asking for a KSeF token/password is also useful, though storage location and output handling are not described.

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?

Four short sentences, front-loaded with the action and resource, then constraints and safety notes. The security reminder earns its place, and there is 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?

The output schema exists, so return-value detail is not required, and the one-parameter signature is simple. The description covers authorization, whitelist filtering, and non-transmission adequately, though it omits where the prepared file ends up and how invoice IDs should be sourced.

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%, so the single invoiceIds parameter is only implied by 'selected cost invoices'. The description does not clarify that IDs must be positive integers, that 1-50 items are allowed, or that IDs typically come from list_cost_invoices, leaving the agent to rely on the raw schema.

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 (prepare) and resource (Elixir-0 transfer file for selected cost invoices on the linked KSeF Płatności account), which distinguishes it from siblings like build_transfer_title or list_cost_invoices. It stops short of explicitly naming an alternative tool, so it is clear but not maximally differentiated.

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?

Implies when to use it (preparing a transfer file for selected invoices) and adds a useful exclusion ('not sent to a bank'), plus the required OAuth scope transfers.prepare. However, it never states when not to use it or which sibling to pick for related tasks such as listing invoices or building a transfer title.

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