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

Annotations already declare destructiveHint=true and idempotentHint=true; the description earns credit by explaining *why* — this is an absolute overwrite, not a delta, which directly explains the idempotency and makes the destructive behavior concrete. It leaves out auth/permission needs and whether a low-stock notification fires immediately, so it is strong but not exhaustive.

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, front-loaded with the 'WRITE:' signal and the overwrite rule, with zero filler. Every sentence carries operational value.

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 mutation with full schema coverage and clear annotations, the description covers the essential risk (overwrite semantics). It does not say whether the updated part is returned or what happens with an invalid part_id, minor gaps given no output schema exists.

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 100%, so the schema already documents all three parameters, including 'quantity' as 'a total' and 'minimum_quantity' as the low-stock threshold. The description reinforces the total-vs-difference distinction but adds little new per-parameter meaning beyond what the schema states.

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 names a specific verb+resource ('set the quantity on hand ... of a part') and scopes the optional low-stock threshold explicitly. The 'WRITE:' prefix and 'PATCH /parts/{id}' immediately separate it from the read-only siblings like upkeep_get_part and upkeep_list_parts.

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?

It gives a concrete precondition — 'read the part first' — routing the agent to upkeep_get_part before calling, and explains what value to pass. It does not state any when-not-to-use case, but the usage context is clear and actionable.

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