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

With no annotations, the description carries the full burden and does disclose the key side effect: the entire quantity of the line is moved, not adjusted. It also discloses the return value ('Returns the updated line'). It stops short of stating whether the change is reversible, what happens to the prior status, or what errors occur for a missing unitId.

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?

Three short sentences, each carrying distinct information, with the core behavior and scope front-loaded before the alternative and the return value. No filler and nothing redundant with structured fields.

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 two-parameter mutation with no output schema, the description covers purpose, valid values, the sibling alternative, and the return shape, which is close to sufficient. The remaining gap is failure behavior, which matters for a mutation with no annotations declaring safety characteristics.

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 0% and the status property has no enum in the schema, so enumerating InStock, Ordered, Outbound, and Damaged is genuinely additive and prevents an invalid call. 'By unit id' loosely ties unitId to identifying a stock line, though the unit-versus-line distinction remains slightly ambiguous.

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 ('Sets the status of an entire stock line by unit id') and immediately scopes it ('moves the full quantity'), which distinguishes it from the sibling that moves partial quantities. An agent can identify the operation 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?

Explicitly names the alternative, move_inventory_unit_quantity, and the exact condition that selects it ('moving only part of a line's quantity'). It also implicitly establishes when-not-to-use this tool, which is stronger guidance than most definitions provide.

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