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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description is fully consistent with that safe, pure-calculation profile. It adds concrete behavioral context by explaining that lead time is aggregated from stages and demand is derived from it, which makes the read-only computation tangible.

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?

The functional sentence is front-loaded and economical. The second sentence about being a free tool and the link is not helpful for tool invocation, so it is minor waste, but the overall description remains short and readable.

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 six optional parameters and no output schema, the description gives a good high-level model but leaves gaps: it does not explain how varianceDays fits into the lead-time total, whether avgDailyDemand is required for the demand output, or what the response shape will be. It is adequate for a simple calculator but not fully complete.

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 100%, so the baseline is 3. The description adds some interpretive value by naming processing, production, shipping, and receiving as lead-time stages and linking 'demand' to the calculation, but it does not mention varianceDays or clarify optionality beyond the schema.

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 uses a specific verb and resource: it 'add[s] up total vendor lead time' from named stages and 'work[s] out the demand' to cover. This clearly identifies the tool's function and distinguishes it from the sibling inventory calculators, which target different metrics.

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 implies when the tool is appropriate—whenever an agent needs vendor lead time or demand-during-lead-time—but it gives no explicit guidance about when not to use it or which sibling alternatives to prefer. Context is clear enough for a simple calculator, but no exclusions or alternative routing are provided.

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