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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description goes beyond that by explaining return-field semantics, including the meaningful edge case that a remaining-count of null means no end date and that a last-run failure reason may be present. It omits any statement about pagination, ordering, or result volume.

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 dense sentence that front-loads the verb and resource, then lists fields in a logical order. It is on the long side and slightly run-on with its parentheticals, but no sentence is wasted. The trailing note about user-typed text is useful and compact.

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?

With no output schema, the description carries the burden of describing returns and does so thoroughly, field by field, including the null-means-unbounded convention and the pause state. The only gap is absence of pagination or ordering behavior, which matters for a potentially long list.

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?

There are zero parameters, so the baseline of 4 applies; the description correctly does not invent parameter guidance. Nothing is required to compensate for, and the schema is empty and fully described by omission.

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 ('Lists the user's recurring invoices') and then enumerates the exact fields returned, which distinguishes it cleanly from siblings like list_invoices and get_invoice. An agent can tell what it retrieves without opening any 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?

Usage is only implied by the name and the zero-parameter schema; there is no explicit statement of when to call this versus list_invoices, get_invoice, or update_recurring_invoice. For a simple list-all tool that may be sufficient, but no alternatives or exclusions are given.

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