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

No annotations, so the description carries the burden. It helpfully enumerates the returned fields (name, frequency, amount, linked account/category, active state, transaction count), but does not state that it is read-only, whether results paginate, or any auth/rate constraints.

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 tight sentences with the core purpose front-loaded and no filler. The trailing isActive sentence is slightly redundant against the schema but still short and scannable.

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 no output schema, the description compensates by listing return fields, and both parameters are covered. Adequate for a simple read-only list tool, though the lack of sibling routing leaves a small gap.

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 both parameters are already documented in the schema; the description's isActive sentence largely restates the schema's 'Filter by active state' text. The enum parameter 'type' (subscription/bill/installment) is not mentioned in the description at all.

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 (List) and resource (subscriptions and recurring bills), plus what the records contain. Clear purpose, but it does not differentiate itself from close siblings like get_subscriptions_summary, get_subscription_by_id, or get_upcoming_subscription_payments.

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?

Only offers 'Use isActive to filter active-only', which is a parameter hint rather than usage guidance. No when-to-use-vs-alternatives or exclusions are given, so an agent must infer this is the unfiltered bulk-listing call from the name alone.

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