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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds real context beyond that: required auth scopes, the conditional nature of the stock balance ('when tracked'), cost field gating, and the preview-stability warning that responses may change without a version bump. Return shape beyond these hints is not described.

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 tight, single-sentence-style block with no filler, and the core purpose ('One product and its current stock balance') leads. The 'Preview API:' prefix is slightly front-loaded noise before the purpose, but it is relevant stability context.

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?

With no output schema, the description does well to identify what comes back (product, stock balance, cost fields) and what auth and stability to expect. It is incomplete on the two required parameters, which are undocumented in both the schema and the description for a tool that is location-scoped.

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% for both productId and locationId, so the description would need to compensate. It says nothing about what either parameter means or that locationId determines which stock balance is returned, leaving an agent to infer the per-location scoping.

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?

Specific verb+resource ('One product and its current stock balance, when tracked') makes the single-item scope clear against the list_products sibling. It does not explicitly name the sibling or note that a locationId is required to scope the fetch, 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?

The description gives prerequisites (requires products:read, stock:cost for cost fields) but never states when to use this versus cliento_list_products or cliento_list_stock_movements. Usage is only implied by 'One product'.

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