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

Annotations already carry readOnlyHint=true and openWorldHint=false, yet the description adds real value beyond them: sort order ('most recent first'), the meaning of `limit`, the status enum values, and the null-condition on `pdf_url` when Stripe has no PDF or is unreachable. It does not discuss pagination or how many rows exist by default beyond the schema's default.

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?

Front-loaded with the scope statement and the when-to-use sentence before any field detail; each sentence serves a purpose. The row-field enumeration is somewhat long and partially duplicates the output schema, which keeps it from a 5.

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 simple read-only list tool with annotations and an output schema, the description covers purpose, trigger, scoping exclusion, ordering, and return semantics. The only real gap is pagination/volume behavior, which an agent might want before requesting a large `limit`.

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 0% and the single `limit` parameter is only glossed as 'max rows', with the default (10) left to the schema. That is enough for a one-param tool but does not compensate for the absence of schema descriptions.

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 your own Nolio invoices') and immediately scopes what an invoice is ('charges Nolio issued you for your platform subscription'), which separates it from athlete-facing siblings like list_athlete_subscriptions. An agent can select it without opening the 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?

Gives a concrete trigger ('when the user asks for their Nolio billing history, receipts or a downloadable invoice') and an explicit exclusion ('These are your invoices only, never an athlete's'). It stops short of naming a specific alternative tool (e.g. list_athlete_subscriptions or nolio_api_read), so it is clear but not fully routed.

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