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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond the annotations: it is cursor-paginated, returns results in reverse chronological order, and requires a numeric user_id rather than a handle. It does not describe the output shape, but an output schema exists, so that burden is lifted.

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?

Four sentences, each earning its place: the core behavior, the use case, the pagination/parameter caveat, and the sibling alternative. The most important scoping information is front-loaded, and there is no filler or repetition of schema content.

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, cursor-paginated list tool with a full output schema and 100% schema parameter coverage, the description is complete. It covers what the tool returns, how to paginate, what input format is required, and how to resolve the prerequisite handle. Nothing an agent needs to call it 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 description coverage is 100%, so the schema already documents both parameters. The description adds meaning by clarifying that `user_id` must be a numeric ID, not a @handle, and that the first page of `cursor` is empty. This goes beyond the schema's generic 'User ID of the user' and 'The cursor to paginate through the results'.

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 states a specific verb ('List'), a precise resource ('verified accounts following a given X user'), and a clear ordering ('reverse chronological order'). It also distinguishes itself from the sibling tool `get_twitter_user_followers` by explicitly noting it returns only verified followers, so an agent can tell them apart without opening schemas.

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 gives explicit when-to-use guidance: 'Use this to gauge the quality rather than the size of an audience — verified followers are a better credibility signal than raw follower count.' It also names the alternative for the complete list (`get_twitter_user_followers`) and instructs the agent to resolve a @handle first with `get_twitter_user_info`, covering both selection and prerequisite behavior.

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