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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered structurally. The description adds genuine behavior beyond that: 200 entries per page, has_next_page/next_cursor paging, and a cost estimate (~$0.0036 per request, usage-based). It stops short of auth/permission requirements or rate-limit behavior, so it is strong but not complete.

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?

The core sentence is front-loaded and every clause about direction and alternatives earns its place. The auto-injected pricing block adds length that is not behavioral guidance, which dilutes an otherwise tight definition.

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?

An output schema exists, so return values need not be explained, yet the description still flags the two pagination fields an agent needs to iterate. Combined with direction, alternatives, page size and cost, nothing an agent needs to call this 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 cursor, pageSize and userName are already documented in the schema, and the description adds no format or syntax detail for them. The phrase 'identified by @handle' loosely maps to userName but the schema lists no required parameters, so the description does not clarify whether the handle is mandatory. Baseline 3 is appropriate.

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 ('List the accounts a given X user follows'), and immediately pins the direction of the relationship with 'identified by @handle'. It explicitly names the sibling that does the opposite direction and the sibling that tests a single pair, so an agent can separate it from the ~30 other get_twitter_* tools without opening a 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?

Gives the analytical use case ('infer a user's interests, information sources, or professional network — who someone follows is usually a stronger signal of intent than who follows them') plus two explicit alternative routes: get_twitter_user_followers for the reverse direction and get_twitter_user_check_follow_relationship for a single pair without paging. When-to-use and when-to-use-something-else are both covered.

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