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

With destructiveHint=true and idempotentHint=false already declared, the description still adds real value: the cancelled invoice remains in the series but becomes void, the external SPV side-effect must be checked separately, and the call is not retried. It doesn't say whether the cancellation can be undone via oblio_restore_document, which is the main remaining gap.

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 capitalised verb and scope, then behavioural consequences, requirements and endpoint in four tight sentences with no filler. The endpoint path is marginally redundant but harmless.

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, open-world mutation with no output schema, the description covers the resulting state, the confirmation gate, and the external SPV consequence — enough for an agent to act safely. Failure behaviour and reversibility (restore availability) are the only unstated pieces.

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%, with cif, series_name, number and confirm all documented in the schema (including the confirm-after-approval rule). The description only restates the confirm:true requirement and the type values, adding little beyond structured data, 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 (CANCEL) plus the exact resource set (invoice, proforma, notice) and even the underlying endpoint. An agent can distinguish this from siblings like oblio_restore_document or oblio_get_document without opening any 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 clear context: confirm:true plus explicit user approval is required, and if the document already reached e-Factura/SPV the agent should check the SPV side. It does not name the inverse alternative (oblio_restore_document) or state when not to cancel, so it stops short of a full when/when-not routing rule.

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