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

Beyond the readOnlyHint annotation, the description discloses the response envelope ({ onetimes }), the pagination model (cursor-based with next_cursor/previous_cursor), page-size bounds (default 50, max 250), and a non-obvious API restriction that other filters are rejected on cursor requests. That last point is exactly the kind of failure-mode context annotations cannot carry.

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 the return shape, then the pagination contract, then the unusual constraint highlighted as IMPORTANT, closing with the REST endpoint. Every sentence carries information an agent needs; none is padding.

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 naming the response key, and it fully specifies pagination mechanics and the cursor-request restriction. An agent has everything required to call this correctly without further documentation.

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 100%, and the description largely restates what the schema already documents (limit default/max, cursor semantics, ISO 8601 date filters). It reinforces the cursor+limit interaction but adds no new per-parameter meaning, 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 and resource ('List one-time (non-recurring) line items') and immediately names the filterable dimensions, which cleanly separates it from siblings like recharge_list_subscriptions, recharge_list_charges, and recharge_list_orders. The parenthetical 'non-recurring' resolves any ambiguity about what a 'one-time' is.

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?

Gives clear operational context: when to use filters (customer, address, created/updated ranges) and, critically, the rule that cursor-based paging must be done with `limit` alone. It stops short of naming an alternative tool or stating explicit exclusions (e.g., when to prefer a search_* sibling), so it is a strong 4 rather than a 5.

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