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

readOnlyHint=true already covers the safety profile, so the bar is lower; the description still adds useful context by disclosing the endpoint (GET /series) and the returned content ('with their next number'), which matters since there is no output schema. It omits auth requirements, pagination, or ordering, hence not a 5.

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?

Three tight sentences with the core purpose front-loaded. One sentence duplicates the schema enum mapping verbatim, which is mild redundancy but the overall structure remains efficient.

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?

No output schema exists, and the description partially compensates by stating that series are returned with their next number, plus the prerequisite relationship to invoice/proforma tools. For a simple one-param read tool this is nearly complete; only auth and result-shape details are absent.

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 the single enum parameter is already documented in the schema, so baseline is 3. The description's 'f = invoice series, p = proforma, c = receipt; omit for all' largely restates the schema enum mapping without adding new meaning.

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 ('List the document series configured in SmartBill Cloud') plus the payload detail that distinguishes it ('with their next number'). An agent can distinguish it from sibling list tools (list_clients, list_taxes, list_warehouses) purely from the name and description.

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?

'Invoice and proforma tools need a series name from here' explicitly routes the agent to this tool as a prerequisite for the create/estimate siblings. It gives clear when-to-use context but no explicit exclusions or naming of a specific alternative tool.

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