beel_set_default_series

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

The description discloses that the tool changes state (marks and unmarks), which is consistent with readOnlyHint=false. It adds detail beyond annotations: unmarking the previous default, rejecting inactive series with 400, and repeating the call being a no-op (matching idempotentHint=true). It does not contradict any annotation and provides useful behavioral context.

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 compact: two sentences of action/constraints, an endpoint line, and pointers to guardrails and docs. It is front-loaded with the purpose and constraints, and every sentence contributes value. The endpoint line is slightly redundant given the tool name but adds precision. No fluff.

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 mutation tool with side effects, the description covers the effect (mark/unmark), the active-series constraint, idempotency, and points to external resources for exhaustive rules. It lacks an explicit return value, but there is no output schema, and the description focuses on the operation's effects. It is sufficiently complete for an agent to call correctly, especially with the guardrail pointer.

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 both parameters are well-described, so the baseline is 3. The description reinforces the semantic role of company_id and series_id (e.g., 'for this company (NIF)') but does not add new syntax or format details beyond what the schema already provides. It does not need to compensate for a coverage gap.

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 clearly states the action: 'Marks an invoice series as the default of its document type for this company (NIF), and unmarks the previous one.' It uses a specific verb, resource, and scope, and mentions idempotency. It distinguishes itself from other series tools by explaining exactly what 'set default' entails, which is not merely a tautology.

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 provides preconditions (series must be active, only one default per company/document type) and points to guardrails and docs for exhaustive rules. However, it does not explicitly compare against the sibling 'beel_ensure_default_series' or state when to prefer this over alternatives. It gives context but no clear exclusions.

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