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

Annotations already establish readOnlyHint=true, so safety is covered; the description goes further by disclosing pagination mechanics ('Paged: pass next_offset as offset'), the encoded status abbreviations (a/c/e/s), and the underlying endpoint GET /package. It stops short of describing default page size or reply shape, but that is minor given the read-only profile.

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?

Purpose and the alias clarification are correctly front-loaded, and every listed field is arguably load-bearing because the schema delegates field names to the description. However, the filter list is an unstructured run-on with no grouping or line breaks, which makes it harder to scan than it needs to be.

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, five-parameter list tool with 100% schema coverage there is no output schema, and the description compensates partially by noting the paged next_offset contract. Return-record contents and default ordering remain unspecified, but nothing required to invoke the tool correctly 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 coverage is 100%, which alone would set a baseline of 3, but the description adds material value the schema explicitly defers to it for: the schema's 'field' property literally says 'the list tool's description names the valid ones', and the description does supply that enum-like list plus the decoding of status codes. It does not restate op semantics, which the schema already handles.

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 concrete verb+resource ('List subscriptions') and immediately resolves the naming ambiguity by noting the API calls them packages, then defines what a subscription is ('recurring billing plans of customers'). This distinguishes it cleanly from chargeover_get_subscription and the other list_* siblings.

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?

Usage is implied rather than stated: the filterable-field list and pagination hint tell the agent this is the tool for broad, filtered retrieval, and get_subscription is the obvious narrow alternative, but that contrast is never made explicit and no when-not-to-use condition is given.

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