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

Adds substantial behavior beyond the annotations (readOnlyHint=false, idempotentHint=false): nothing is issued until approval, the approval is confirmed with manage_action, results are retrievable via get_action, and it deliberately does not send to SPV/e-Factura or touch the seller's Oblio setting. No contradiction with 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?

Front-loads the '[Invoicing changes]' context and the core purpose, then layers workflow, tax semantics, and integration caveats. Efficient overall, though the bracketed prefix and dense multi-clause sentences make it slightly heavier than needed.

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?

An output schema exists, so return values need not be explained, and the description still tells the agent where the series/number/PDF link surface (get_action). For an 11-parameter, nested, non-idempotent mutation it covers the critical caveats; remaining gaps are the uninstructed optional fields.

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 55% schema coverage, the description compensates on the most error-prone parameter: prices are WITH VAT unless vat_included is false, and it clarifies doc_type is invoice-or-proforma. It adds real meaning beyond the schema, though currency, language, due_date, and mentions remain undocumented in both places.

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 (propose issuing) and resource (invoice or proforma), and the 'propose/simulated' framing clearly separates it from invoices_issue_for_order and invoices_cancel. An agent can identify the operation and its scope without opening the 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?

Explains the surrounding workflow explicitly: the action is simulated, requires seller approval via manage_action, and the result feeds orders_attach_invoice. It names the sibling that consumes its output, though it never states when to prefer this over invoices_issue_for_order, so no explicit exclusion.

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