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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is covered. The description adds the 'newest first' ordering and a sketch of the returned metadata (email, status, plan, amounts), which is genuine context. However, it never explains pagination/limit behavior or what include_samples does, which are non-trivial behavioral traits with no annotation coverage.

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 sentences, zero waste, with the core behavior and return shape front-loaded before the sibling routing hint.

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 list tool with no output schema, the description gives the ordering, the filterable dimensions, and the returned fields. It falls short only on the limit/include_samples parameters and pagination expectations.

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 0%, so the description bears the full burden. It names app_id, status, and payment_type only as filters, adding no meaning beyond the property names, and it omits limit and include_samples entirely. An agent could not infer the default page size or what sample data inclusion changes.

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/registrations), plus the implicit sort order 'newest first'. Sibling tools list_plans, list_coupons, and list_recent_cancellations make the resource distinction essential, and the description draws it clearly.

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 routes the agent: use get_customer for a single user or revenue_summary for totals, leaving this tool for enumeration and filtering. The optional-filter sentence makes the intended usage unambiguous.

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