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

No annotations are supplied, so the description carries the full burden. It does disclose a genuinely non-obvious behavior: money-type values and currency are nulled unless the caller has see_prices, while key and type remain visible, and empty required fields are surfaced. It does not state that the operation is read-only, what permissions otherwise apply, or what happens when the target/object does not exist.

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 tight sentences with no filler, and the permission caveat is placed where it matters. The opening is a fragment rather than a stated action, which costs a little clarity, but nothing is redundant.

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 three-parameter read tool with no annotations and no output schema, the description covers the surprising part (permission-based nulling of prices) but leaves the parameters undefined and the return shape only loosely implied. It is minimally adequate but not complete.

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% across three required parameters, so the description needed to compensate and does not. It never explains that 'target' selects the object type (customer, property, job, quote, invoice), nor that shop_id and object_id are UUIDs identifying the shop and the record; only 'on one record' loosely implies object_id.

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 identifies a specific resource and scope: custom field values for a single record, plus which required fields are still empty. It never names a verb (retrieve/read) and never names siblings like fields_list or fields_define, so an agent must infer that this is the per-record read counterpart, but the resource and scope are unambiguous.

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?

There is no when-to-use guidance and no mention of alternatives, despite three closely related siblings (fields_list, fields_define, fields_set). The phrase 'on one record' hints at the distinction from a list tool but does not state it, leaving the agent to infer routing.

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