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

Annotations only declare it is non-read-only and non-destructive; the description adds substantial behavior beyond that – the max(start, last+1) rule, the guarantee against duplicates, null semantics, and the return value. This is exactly the extra context an agent needs for a 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?

Four dense sentences with zero filler; the core purpose is front-loaded and the caveat plus alternative follow in logical order.

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?

Complete for a single-parameter mutation with no output schema: it covers what changes, edge cases (null, values below existing quotes), the return value, and the boundary with the sibling tool.

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 0%, so the description carries the full burden: it defines what start_number means, how it interacts with existing quotes, and that null resets to 1, compensating fully for the bare 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 ('Set the first number of the quote series') and immediately scopes the function (quote numbering only, not invoices). An agent can distinguish it from set_invoice_series 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 a concrete usage scenario ('2299 to continue from another program'), explains the null reset case, and explicitly routes to the alternative set_invoice_series for invoice numbering.

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