cancel_invoice

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

With no annotations, the description carries the full burden and does disclose the key consequence: the invoice stays in the records but is not counted, and delivery to the customer changes the correct action entirely. It does not cover permissions required, whether the cancellation is itself reversible, or any rate/duplicate-call concerns, which is a real but modest gap for a destructive mutation.

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, effect first, exception second, with no filler. The phrasing is slightly terse and the split into a fragment as the second sentence is a little clipped, but nothing is wasted.

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 two-parameter mutation the description covers the effect on data, the user-intent prerequisite, and the branch to the sibling tool; an output schema exists so return values need not be explained. Only authorization and reversibility are unaddressed, which is a minor residual gap given no annotations are supplied.

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% and both parameters are documented in the schema, including a concrete example for 'reason'. The description adds no further meaning about the number format or what makes a good reason, so the baseline 3 applies.

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 ('Stornuje vydanou fakturu') and immediately disambiguates scope from the nearest sibling by naming issue_credit_note as the alternative path. An agent can distinguish cancel_invoice from issue_credit_note without opening either 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?

Gives an explicit precondition ('Jen pokud ji uživatel výslovně ruší') and an explicit exclusion with the substitute tool ('Pokud už byla doručena odběrateli, nestornuj — vystav dobropis přes issue_credit_note'). Both the when and the when-not, plus the named alternative, are present.

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