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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the description only needs to add context. It does add the return shape ('Returns customer + the segment metric'), which is meaningful given no output schema exists. It stops short of noting limits on the 180-day window configurability or result ordering for the ltv method.

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 clauses, front-loaded with the tool's action, then mode definitions, then return shape. No filler sentences and nothing repeated from the schema.

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 small two-parameter read tool with no output schema, the description supplies the essentials: what it does, mode meanings, and what comes back. The only minor gap is ordering/ranking behavior for the ltv segment, which an agent might need to interpret results.

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 baseline is 3, but the description adds semantics the schema does not: it defines what each enum value actually selects for, whereas the schema only says 'Segmentation method.' The limit parameter's range is left to the schema, which documents it adequately.

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 ('Segment customers') and immediately defines the two segmentation modes, which lets an agent distinguish it from generic finders like find_customers or lookup_customers. However, it never names or contrasts with the closest sibling (churn_risk), so sibling differentiation is only implied by the method list.

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 explains what each method value means ('top customers by lifetime collected payments', 'no job in 180 days'), which guides selection between the two modes. It gives no guidance on when to prefer this tool over neighbors like churn_risk or revenue_by_month, so usage is implied rather than stated.

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