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

Annotations already declare readOnlyHint=true / destructiveHint=false / openWorldHint=true, so the safety profile is covered. The description goes further by disclosing the returned fields (gov_status, KSeF number, send date, error messages), the null-status semantics, and an auth requirement (Cotlet API key with access to this app), which is real behavioral value beyond the annotations.

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 purpose and returned fields are front-loaded, and the auth note sits at the end. There is mild redundancy in listing the states twice ('not sent, processing, accepted or an error' followed by 'ok, processing, send_error, server_error, offline and not_connected'), but overall it stays on point.

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 read-only single-parameter status tool with no output schema, the description covers what the tool reports, the value semantics, and its auth requirement, leaving little an agent would need before calling it. Only the explicit call-ordering guidance 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% with a single documented invoice_id ('Invoice ID from list_invoices'), so the schema already carries the parameter meaning. The description adds no additional parameter guidance, which is the baseline expectation.

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 gives a specific verb+resource ('Where an invoice stands in KSeF') and enumerates the possible states, so an agent knows exactly what status retrieval means here. It is cleanly distinguishable from the sibling write action fakturownia_send_invoice_to_ksef and from the generic fakturownia_get_invoice.

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 the use case (checking where an invoice stands in KSeF) but never states when to call it versus alternatives such as get_invoice, nor any prerequisite ordering relative to send_invoice_to_ksef. Usage is inferable but not explicit.

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