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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description still adds the pagination trait ('Paged') and, importantly, enumerates the returned fields in the absence of an output schema, which is genuine added context beyond the 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?

A single compact sentence that front-loads the core purpose, then the returned shape, then the pagination note. Every clause carries information and nothing is padding.

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 12-parameter, zero-required read tool with no output schema, the description usefully enumerates return fields and notes pagination, which compensates for the missing output schema. It falls short only on usage guidance relative to sibling list tools.

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%, so all 12 parameters are already documented with types, ranges, and semantics (e.g. next_page usage, per_page default). The description only echoes the cycle enum values and a couple of fields, adding nothing beyond the schema; baseline 3 applies.

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 ('List') and resource ('recurring invoices'), adds the German synonym 'Abo-Rechnungen' to remove ambiguity, and names the returned fields (name, cycle, client, next run). It is clearly distinguishable from billomat_list_invoices and the other list_* siblings.

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?

Usage is only implied by the resource name; there is no explicit statement of when to prefer this over billomat_list_invoices or billomat_get_invoice. No prerequisites, exclusions, or alternatives are given, so the agent must infer intent.

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