twitter_users_by_usernames

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, signaling a safe read operation. The description adds useful context: batch size limit (up to 100), return shape, and authentication requirement (X_BEARER_TOKEN). It doesn't detail pagination or error behavior, but for a lookup tool with strong annotations, this is sufficient.

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?

Three crisp sentences: what it does, what it returns, and auth requirement. No filler. Front-loaded with the core action. Every sentence earns its place.

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?

The tool is simple with 2 params, no output schema, and good annotations. The description covers purpose, return shape, and auth. It lacks mention of error cases or rate limits, but for a read-only batch lookup, the provided info is largely sufficient. A small gap is not specifying the format of the returned data (e.g., 'data' field) more explicitly, but it's enough.

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%, with both parameters described in the schema. The description does not add parameter details beyond the schema, but the schema's own descriptions are clear (handle without @, up to 100; user fields as CSV). The description's return fields hint at what user_fields might include (name, username, public_metrics) but not extensively. 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?

The description clearly states the tool does a batch profile lookup by handles with a max of 100. It specifies the resource (Twitter users) and the verb (lookup), and provides the return shape. Among siblings like twitter_user_by_username and twitter_search_recent, this is distinct as a batch handle lookup.

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 implies usage: when you have handles and need batch profiles, use this. It doesn't explicitly mention when to use alternatives like twitter_user_by_username for single lookup, but the batch limit and return fields give clear context. No exclusions are stated.

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