ls_list_subscription_items

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

Annotations already declare readOnlyHint and destructiveHint, so the description adds value by disclosing pagination behavior and the cross-store constraint. The explanation of meta.page and the environmental variable requirement goes beyond what annotations convey, earning a 4.

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?

The description is front-loaded with the main purpose and then adds pagination and cross-store context. The final sentence about the scoped API key is a bit awkward and verbose, but overall the description is efficiently structured and not excessive.

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?

Given the tool has no output schema, the description compensates by mentioning pagination response fields. It covers the main purpose, optional filters, cross-store restrictions, and security boundary, which is sufficient for an agent to invoke the tool correctly. Minor gap: no mention of the array of items itself, but that is implied.

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?

The input schema has 100% description coverage for all five parameters, so the description doesn't need to add much. It restates that filters apply to subscription or price, which aligns with subscriptionId and priceId, but adds no new parameter-level detail. Baseline 3 is appropriate.

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?

The description clearly states the tool lists subscription items, optionally filtered by subscription or price. This is a specific verb+resource that distinguishes it from singular getter tools like ls_get_subscription_item and other list tools for different resources.

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?

The description provides clear context for the tool's use case (listing subscription items with optional filters) and includes a significant cross-store configuration note about required parameters. It does not explicitly name alternative tools, but the sibling set and name make the distinction obvious, so it earns a 4.

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