issue_invoice

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

With no annotations supplied, the description carries the full burden and does disclose meaningful behavior: the exact output format/version, that the invoice is persisted to the records, and that a summary is returned. It omits whether issuing consumes the next number from the sequence, whether the operation is reversible, and what permissions are needed.

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?

Two short sentences: the first front-loads what the tool produces and persists, the second front-loads the prerequisite checks. Nothing is redundant.

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 19-parameter mutation tool with an output schema and full schema coverage, the description covers the essentials: outputs, persistence, and the pre-flight validation steps. It could go further on numbering behavior and reversibility/cancellation, but the core is present.

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 100%, so all 19 parameters, including the vat_rate and currency defaults and the customer ID source, are already documented in the schema. The description only reinforces where customer_id comes from (list_customers); it adds no line-item or rounding semantics beyond the 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?

The description gives a specific verb and resource ('Vystaví fakturu') and even names the concrete artifacts produced (PDF/A-3a, ISDOC 6.0.2, QR Platba+F) plus the side effect of storing it in the records. It does not, however, distinguish this tool from close siblings such as add_manual_invoice or issue_credit_note, so an agent still has to infer the boundary from the names alone.

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?

It states a real precondition workflow: verify the customer with list_customers / lookup_company and confirm the amounts with the user before issuing. That is clear when-to-use context naming actual sibling tools, but there is no guidance on when NOT to use it (e.g. versus add_manual_invoice or cancel_invoice).

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