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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered by structured data. The description adds context beyond that: it names the required auth ('Cotlet API key with access to this app') and frames the call as the read-before-write step in a plan-change flow.

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 with purpose, then returns, then usage and auth. Four sentences that each carry information, though the return-value enumeration is a touch long; nothing is 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?

No output schema exists, so the description's enumeration of returned fields (item prices/quantities, coupons, billing dates, scheduled change) is exactly what an agent needs to use the result. Auth requirement is stated. Complete for a single-param read tool.

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 there is only one parameter, whose description ('Subscription ID from list_subscriptions') already documents origin. The description adds nothing about the ID format or source, so 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 one subscription) and immediately clarifies scope with 'One subscription', distinguishing it from chargebee_list_subscriptions. It further enumerates what the object contains (items, coupons, scheduled change), so an agent knows exactly what it retrieves.

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?

Explicitly says to read it before changing a plan or cancelling, which routes the agent relative to chargebee_change_subscription_plan and chargebee_cancel_subscription. No named exclusions or explicit alternatives, so not a full 5, but the when-to-use context is clear.

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