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

The annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context not present in annotations: 'Works without a connected store,' telling the agent no store connection or live data is required.

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 sentences, front-loaded with the usage trigger, followed by a compact but relevant list of supported metrics. Every sentence earns its place and nothing is wasted.

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 single-parameter read-only lookup tool with an output schema, the description covers what the tool does, when to use it, what terms are supported, and that no store connection is needed. Nothing an agent needs to call it correctly is missing.

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 metric parameter is already documented with examples. The description adds a much broader list of accepted terms (safety stock, urgency bands, ABC class, EOQ, fill rate, etc.), effectively serving as an example inventory without needing an enum. That adds meaning beyond the schema's two examples.

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 states a specific verb ('explain') and resource ('inventory planning term' / 'how Forthcast calculates it') and lists concrete metric names. This clearly separates it from calculation siblings like calculate_reorder_point and calculate_order_quantity, which perform math rather than provide definitions.

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 an explicit trigger: 'Use this when someone asks what an inventory planning term means or how Forthcast calculates it.' It also clarifies that it 'Works without a connected store,' which helps an agent know it can be used in unauthenticated contexts. It does not explicitly exclude calculation siblings, which keeps it from a 5.

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