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

Annotations already declare readOnlyHint=true, and the description merely restates 'Read-only', which adds no new information. It does add modest context by naming the underlying endpoint and the shape of returned fields, but says nothing about pagination behavior despite page/per_page parameters, nor about rate limits or empty results. With annotations covering the safety profile, a 3 is fitting.

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 short clauses with no padding, front-loading the resource and the returned fields. The endpoint citation is mildly redundant but harmless and compact; nothing is buried.

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 fully optional-parameter, read-only list tool with 100% schema coverage and no output schema, the description plus annotations supply what an agent needs to call it. The only soft spot is the absence of any pagination or filtering narrative, which is minor given the schema's explicit per_page and sort documentation.

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 seven parameters (page, sort, number, status, client_id, client_status, per_page) are already documented in the schema. The description adds no syntax, format, or filtering semantics beyond that, so the 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 invoice schedules) and enumerates the key fields returned (frequency, next send date, remaining cycles). This implicitly distinguishes it from invoiceninja_list_invoices, though it never names that sibling explicitly to sharpen the contrast.

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?

The description offers no when-to-use guidance, no exclusions, and no pointer to alternatives such as list_invoices or get_invoice. Usage is only inferable from the verb 'List' and the read-only label; nothing tells the agent when recurring schedules are the right target.

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