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

Annotations already cover read-only, idempotent, non-destructive, open-world behavior, so the safety profile is known. The description adds one genuinely useful fact beyond them: only public profiles are returned. It says nothing about ordering, partial failures, or handling of nonexistent/private ids in a batch.

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?

One sentence, front-loaded with the verb and resource, no filler. The batch cap and 'already named' constraint both earn their 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?

With no output schema, the description's 'public profiles' is the only signal about return content, leaving the profile fields unknown; batch semantics (order preservation, missing ids) are also unaddressed. It is adequate for a simple batch read but not fully 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 coverage is 100% and there is a single parameter, so the schema already documents the array, its item type, and the 1-20 bounds. The description reinforces that ids must be numeric and already known to the user, but adds no syntax or formatting detail beyond that.

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 gives a specific verb ('Look up') and resource ('public profiles') and bounds the input ('up to 20 numeric user ids'). 'Ids the user already named' implicitly separates it from search_users-style discovery, though no sibling is named explicitly.

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 'the user already named' implies the correct usage condition (you already have handles/ids and want profile data), which implicitly rules out discovery flows like search_users. However, no alternative is named and no exclusion or prerequisite is stated outright.

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