get_user_info

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds the constraint that exactly one identifier must be provided, but it does not disclose what happens when both are provided, nor any error behavior, rate limits, or read-only guarantees. The description is not misleading, but it provides limited behavioral insight beyond the basic lookup semantics.

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 description is concise and front-loaded: the first sentence states the core purpose, followed by a clear usage constraint and two short parameter descriptions. Every sentence earns its place with no redundant or filler content.

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 simple lookup tool with an output schema present, the description covers the essential input semantics and invocation constraint. It does not mention edge cases or error handling, but given the simplicity of the operation and that the output schema exists, it is sufficiently complete. Slightly more detail on return behavior would warrant a 5, but the current level is adequate.

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 0%, so the description must compensate. It does so effectively: 'screen_name: Twitter username (without @)' clarifies the format (no @) and 'user_id: Twitter numeric user ID' specifies the numeric nature. It also explains the mutual exclusivity requirement, which is essential for correct invocation. This adds significant meaning beyond the raw schema.

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's function: 'Get a user's profile metadata by screen name OR numeric user ID.' This uses a specific verb ('Get') and resource ('profile metadata'), and the two identifier options are explicitly mentioned. It also distinguishes itself from sibling tools like get_user_followers or search_user by focusing on profile metadata for a single user.

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 provides clear context on how to use the tool: 'Caller must provide exactly one of screen_name / user_id.' This is a critical usage constraint. However, it does not explicitly mention when to use this tool versus alternatives like search_user or get_user_tweets, so it falls short of a 5.

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