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

Annotations already establish a safe read (readOnlyHint=true, destructiveHint=false), and the description adds genuine context beyond them: the smallest-currency-unit convention (5000 = $50.00), the meaning of auto_collection, and the required Cotlet API key scope. It does not contradict the annotations.

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?

Front-loaded and generally efficient: the return statement comes first, followed by only the details an agent needs (currency units, auto_collection, auth). The opening fragment 'One customer with tax status...' is slightly loose but not wasteful.

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 read-only single-param tool with no output schema, the description supplies enough about what comes back (tax status, credits, payment collection setting) plus auth and currency conventions. It is close to complete, missing only explicit sibling routing.

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 single parameter is fully documented, so baseline 3 applies. The description explains returned fields rather than adding meaning to customer_id, so it neither over- nor under-delivers on the parameter itself.

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 and resource: 'Returns the customer record behind a customer ID.' The phrase 'behind a customer ID' hints at the distinction from chargebee_find_customer, but the sibling is never named, so differentiation relies on inference.

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?

Usage is only implied. The schema note 'Customer ID from find_customer' gestures at the lookup-then-fetch workflow, but the description itself gives no explicit when-to-use or when-not-to-use guidance relative to find_customer.

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