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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context: the response is keyed by SKU and it requires a Cotlet API key with access to this app, which is an auth prerequisite an agent cannot infer from the schema. It does not mention rate limits or pagination, keeping it from a 5.

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 tight sentences, front-loaded with what the tool returns before moving to the parameter and the auth note. Only the redundant 'Faire:' prefix and minor overlap with the schema on skus keep it from a 5.

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 the work of explaining the return shape (on-hand quantity keyed by SKU) and the auth requirement. For a single-parameter read tool with annotations covering safety, that is nearly everything an agent needs; only pagination/volume behavior for the no-skus 'all variants' case is unaddressed.

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% and the sole parameter already documents 'SKUs to check. Default: all variants.' The description's 'Pass skus to check only some variants' merely echoes that, adding no format, casing, or limit detail, so the baseline 3 applies.

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+resource (get inventory) and narrows it to on-hand quantity per variant, keyed by SKU, so an agent knows exactly what data comes back. It implicitly contrasts with the sibling faire_update_inventory through its read-only framing, but never names an alternative explicitly, so it stops 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 only usage guidance is 'Pass skus to check only some variants,' which restates the parameter's default behavior rather than telling the agent when to use this tool versus faire_update_inventory or the order-listing tools. No prerequisites, exclusions, or alternative routing are given.

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