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

Annotations only flag destructiveHint=true, but the description goes far beyond: fiscal/NAV nature, irrevocability, cancel-not-delete semantics, call_id idempotency with the specific vendor error 338, and the no-auto-retry protocol. This is exactly the behavioral context the annotation cannot convey.

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 core action and the irrevocability warning, then layered with operational detail. Every sentence carries distinct information, though the density approaches the upper bound of what an invocation-time description should hold.

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 destructive, non-idempotent fiscal write with no output schema, the description covers safety profile, idempotency, error recovery, and prefix constraints. Nothing critical to correct invocation is left implicit.

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?

With 100% schema coverage the baseline is 3, but the description adds real meaning: it explains how gross_total and vat_rate drive the derived net/VAT/unit price, clarifies that the prefix must be a receipt-only prefix, and states call_id's uniqueness requirement. It does not, however, elaborate on payment_method, order_number, or comment 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?

States a precise verb and resource: 'ISSUES a real HUF receipt (nyugta)'. It explicitly differentiates itself from the invoice path ('must be a receipt-only prefix... not an invoice prefix') and from its cancellation sibling, so an agent can route correctly without opening a 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?

Names the alternative for cancellation (szamlazz_reverse_receipt) and gives explicit retry guidance (never auto-retry; repeat with the SAME call_id). Missing only an explicit statement of when to prefer this over szamlazz_create_invoice; the distinction is implied through the prefix rule rather than stated directly.

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