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

With no annotations, the description carries the full behavioral burden. It usefully discloses scope: volume aggregates across all locations under the same owner, and band comparison is owner-or-office. But it doesn't explicitly state this is a side-effect-free read or clarify permissions, so a 3 is appropriate – it adds meaningful scope context but stops short of full behavioral disclosure.

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?

Two efficient sentences that front-load the returned picture and end with the key omission rule. The brand phrasing ("Doing Work") adds a small parsing cost but no sentence is wasteful.

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?

An output schema exists, so return values needn't be spelled out, and the description still gives a helpful behavioral preview plus the optional-parameter rule. The only real gap is the unexplained shop_id, which is minor relative to the schema and output schema coverage.

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 coverage is 50%: amount_minor is documented in the schema, and the description adds real value by explaining what happens when it's omitted. But shop_id is undocumented in both schema and description, and its role ('the shop' in the band line) is only implicitly referenced.

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 makes clear this computes a fee preview: what the platform would take on a payment of this size, the effective rate, the month's volume, and proximity to the next cheaper band. It's a specific computation previewed, though the phrasing is output-centric ("What Doing Work would take") rather than an explicit verb, and doesn't distinguish itself from siblings fees_statement or fees_schedule.

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?

"Leave out amount_minor for just the month picture and the next band line" gives a clear conditional usage rule for the optional path. However, there's no explicit guidance on when to use this versus fees_statement or fees_schedule, leaving the agent to infer the distinction.

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