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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description goes well beyond them by disclosing the 404 conditions (nonexistent or protected account and why protected accounts are invisible), the per-account billing, and the extra first-page profile-lookup charge. It stops short of describing the returned payload's fields, which keeps it off a 5.

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 likely-empty caveat are front-loaded, followed by failure modes, then cost, then pagination — a sensible order. The cost sentence is dense with repeated credit figures, but each clause carries operational information an agent needs before calling.

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 still tells the agent what to expect back (profiles plus meta.nextCursor) and how to continue pagination. Failure modes, cost, and pagination are all covered for a three-parameter read tool, leaving nothing material unstated.

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%, so the baseline is 3, but the description adds genuine meaning: `user` is resolved via a billed profile lookup on the first page, and `cursor` carries the resolved account so later pages skip that charge. That cost-coupled behavior of the cursor parameter is not visible in the schema.

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 — the creators an X account pays to subscribe to — and adds the qualifying condition that hidden subscriptions are omitted. This is distinguishable from adjacent siblings like get_x_user_following or get_x_user_affiliates without opening any schema.

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?

It sets expectations ("Often empty") and explains when to call again with the cursor, which is real usage guidance. However, it never routes the agent between this tool and alternatives such as get_x_user_following or get_x_user_affiliates, so the choice is left to inference from the tool name.

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