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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the filterable dimensions and the backing endpoint (GET /v1/subscriptions/), but says nothing about pagination behavior or result ordering beyond what annotations and schema 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?

Two compact sentences, front-loading the verb+resource and the filter dimensions, with the endpoint noted last. No filler, though the endpoint string is only marginally useful.

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 full schema coverage and a readOnlyHint annotation, the description is essentially sufficient; the absence of return-format detail is fine since no output schema exists but the operation is a straightforward list. Only explicit pagination/ordering guidance is missing.

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%, so all 8 filters are already documented with their own descriptions (including the useful organization_id token-span note). The description merely restates a subset of those filters (customer, product, status, active, cancellation) and adds no syntax or format detail, 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 (List) and resource (subscriptions), and enumerates the filterable dimensions. It does not explicitly differentiate itself from the sibling polar_get_subscription (single-resource fetch), so routing depends on the agent's own inference.

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?

No when-to-use or when-not guidance is provided; nothing tells the agent this is for browsing/filtering multiple subscriptions versus fetching one. The filter list is descriptive but not prescriptive about context.

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