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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds material context beyond them: billing ('1 credit + 1 credit per user_result returned'), result ordering by X, and cursor termination semantics. The credit cost per returned user is exactly the kind of pre-call cost signal an agent needs.

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 and return shape, then billing, then pagination — good ordering. The final sentence ('when meta.nextCursor is set, call again with cursor set to it') is largely redundant with the earlier 'paginate with meta.nextCursor, which is null after the last page', costing a small amount of efficiency.

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 carries the burden of describing results and does explain the accounts plus meta.nextCursor pagination and per-result billing. It stops short of indicating what fields each returned account carries, which is the one remaining gap for an agent consuming the response.

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 the schema already documents id format, limit bounds, and cursor opacity/rejection behavior in more detail than the description. The description's pagination sentences add flow guidance but largely restate the cursor parameter's documented contract, 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 ('get') and precisely scoped resource ('the members of a public X List'), then clarifies the return is 'the accounts in a List, as X orders them'. This cleanly separates it from siblings like get_x_list (list metadata) and get_x_list_posts (posts in a list) without needing to name them.

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 a positive usage rationale — 'Lists are curated, so this is a quick way to find the accounts that matter on a topic' — and full pagination instructions. It does not name exclusions or point to alternative sibling tools (e.g., get_x_user_followers) when a List isn't the right source.

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