get_user_by_id

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

With no annotations provided, the description must carry the behavioral burden, and it does convey that this is a read-only retrieval operation. However, it does not disclose authentication requirements, rate limiting, or behavior for non-existent or private users, which are relevant gaps for a live API tool. The core behavior is clear, but the description is thin on consequences and edge cases.

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?

A single sentence with no filler or repetition. The verb, resource, and lookup key are all present and front-loaded, so an agent can parse the definition quickly.

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 one-parameter read tool the description is adequate, but it leaves out what information is returned, whether authentication is needed, and what happens for unknown IDs. Since there is no output schema and no annotations, this missing context is not supplied elsewhere, so the description is only minimally complete.

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%: the user_id parameter is already documented as 'Twitter user ID'. The tool description simply repeats this notion ('by user ID') without adding format details, whether the ID is a numeric string, or how it relates to the returned user record. Baseline 3 applies because the schema handles the parameter documentation.

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 ('Get'), resource ('Twitter user information'), and lookup key ('by user ID'), which clearly distinguishes it from siblings like get_user_by_username, get_user_tweets, and get_tweet_by_id. The combination of resource and identifier leaves no ambiguity about what this tool retrieves.

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 phrase 'by user ID' gives a clear context for when this tool applies: when the caller has the user ID rather than a username or tweet ID. It does not explicitly name alternatives or state when not to use it, but the ID-based lookup condition is enough to route an agent correctly among the listed siblings.

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