get_user

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

With no annotations, the description must carry the burden of disclosing behavior. It does mention the return type ('raw user object') and specific fields, which is useful, but it doesn't disclose potential side effects, authentication needs, or error behavior. The read-only nature is implied by 'look up,' but not explicitly stated.

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 two sentences, front-loaded with the action, and contains no filler. Every word adds value, effectively showing what the tool does and what it returns.

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?

This is a simple tool with one parameter and no output schema. The description adequately explains the return format ('raw user object') and the lookup method. It could mention rate limits or error cases, but for a straightforward profile lookup, it is sufficiently 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?

The schema already covers the single parameter fully with a description ('Handle without the @.'). The tool description adds 'by @username,' which is redundant. Thus the description adds no meaningful parameter semantics beyond what the schema provides, so 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 action ('Look up a user profile') and the specific resource ('by @username'). It distinguishes itself from sibling tools like get_user_tweets or get_followers by focusing on the profile object itself, making the purpose unambiguous.

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 gives clear context for when to use the tool (to retrieve a user profile by username) but does not explicitly mention alternatives or when not to use it. For instance, it doesn't say 'to get a user's tweets, use get_user_tweets.' This is a minor gap.

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