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

With no annotations, the description carries full behavioral burden. It does disclose the payload shape and hints at role scoping via '(owner or office)', which is real added context, but it says nothing about read-only nature, permission requirements for non-owner callers, or what happens when a month has no activity.

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 with the subject (monthly fee statement for a shop) front-loaded and the payload contents enumerated afterward. The trailing parenthetical '(owner or office)' is slightly cryptic and costs a bit of clarity.

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?

No output schema and no annotations exist, so the description correctly spends its words enumerating the returned fields, which is the most valuable thing it could do here. Gaps remain around permission model and month formatting, but the omission is minor for a two-parameter read tool.

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%, so the description must compensate. It ties the two params to meaning ('a month's' and 'for a shop'), but it never states the expected month format (the schema's YYYY-MM pattern) or what shop_id refers to beyond 'shop', leaving the agent to read the schema.

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?

Names a specific resource and scope: a one-month fee statement for a single shop, and enumerates exactly what it returns (card/bank volume, fees by kind, effective rate, line items, distance to next band). It never mentions the adjacent fees_preview or fees_schedule, so an agent must infer the boundary itself, which keeps it short of a 5.

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: 'a month's ... for a shop' and the parenthetical '(owner or office)' hint at who may call and what data is included, but there is no stated when-to-use versus fees_preview or fees_schedule, and no prerequisites or exclusions.

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