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

Annotations already mark the tool as destructive, and the description adds meaningful consequences beyond that: changing the prefix or format closes the old series, start_number is rejected once a finalized invoice exists because Veri*factu forbids gaps, and R/S prefixes are reserved. It also states what the return value previews.

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?

The description is front-loaded with the core action, then layers in template semantics, side effects, and the quote-series alternative. Despite its length, every sentence carries operational information needed to avoid numbering mistakes.

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 mutation tool with three optional parameters and no output schema, the description covers purpose, template semantics, side effects, constraints, and return preview. Nothing an agent needs in order to invoke it safely appears to be missing.

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 coverage is 100%, so the baseline is 3, but the description adds substantial meaning beyond the schema: it explains the template tokens, year-token behavior, continuous vs yearly numbering, and the restriction on when start_number is accepted. The invoice_prefix parameter is only partially enriched via the reserved-prefix rule.

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 states a specific verb and resource: setting the invoice numbering series. It also distinguishes the tool from quote numbering by explicitly pointing to set_quote_series, so an agent can route correctly without opening schemas.

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 gives explicit usage context: use start_number to continue from a previous program, changing prefix or format opens a new series, and quote numbering is handled by a separate sibling tool. The alternative and relevant conditions are named directly.

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