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. The description adds genuinely new behavioral context beyond that: approximate result volume (~20 per page) and the pagination model, which directly affects how the agent loops. Remaining gaps such as rate limits are minor.

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?

Two short sentences with zero padding; the core capability is front-loaded and the pagination hint follows immediately. Nothing in the text needs removal.

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, four-parameter list tool with full schema coverage, the description plus schema plus annotations give an agent enough to call it correctly, including page size and the next_cursor loop. The only soft spot is that no output schema exists and the shape of returned tweets is not characterized.

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 all four parameters including cursor, userName, sinceTime, and untilTime are already documented in the schema. The description only reinforces cursor usage and adds no format or semantic detail (e.g., that sinceTime is inclusive) beyond what the schema states, so the 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?

The description names a specific verb and resource ('Get tweets mentioning a user'), and the word 'mentioning' implicitly separates it from siblings like get_user_timeline or get_user_last_tweets that return authored tweets. It does not explicitly name or contrast any sibling, so it falls short of a 5.

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 second sentence gives operational guidance ('Use cursor to paginate'), which is useful but is about how to paginate rather than when to choose this tool over alternatives. There is no statement of when-not to use it or which sibling to prefer for a user's own posts.

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