Get Users By Usernames

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

Annotations already declare read-only, idempotent, non-destructive, open-world, and the description adds real operational context beyond them: API key requirement, one request per call, roughly 1 unit of cost with a per-result cost estimate, and the fact that unresolved accounts surface in completeness.notReturned rather than erroring. That is exactly the added-value layer annotations cannot express.

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 tight sentences in a single paragraph: capability and limit first, failure behavior second, sibling routing third, cost/auth last. No filler and nothing buried.

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 annotations, a fully described input schema, and an output schema, the remaining unknowns for an agent are cost, auth, partial-failure behavior, and batching limits — all of which the description covers. Nothing needed 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 both parameters are already documented; the description's mention of usernames/@handles/profile links and the 100-item cap largely restates the schema. responseFormat is left entirely to the schema, so no extra semantic value is contributed here.

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 ('Fetch up to 100 public user profiles') plus the accepted identifier forms (username, @handle, profile link). It also names the sibling to use instead for numeric IDs, so an agent can distinguish it from the many other user 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 an explicit alternative rule ('Use tweetapi_user_by_ids when you have numeric IDs') and a hard batching limit of 100. It does not address when to prefer the singular tweetapi_user_by_username sibling, which is the closest neighbor in the catalog, so the routing guidance is strong but not exhaustive.

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