get_users

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

Annotations already declare readOnlyHint=true, but the description adds valuable specifics: it confirms read-only behavior, lists error conditions (missing resources, invalid identifiers, insufficient permission, rate limits), and notes that these return as errors. This goes beyond the annotation's boolean by explaining expected failure modes.

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 front-loaded with purpose and usage, but contains redundant statements (e.g., read-only repeats the annotation) and an entire second half about non-existent parameters. It could be trimmed to the first two sentences; the trailing clause about project_id/group_id is irrelevant and wastes attention.

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 tool with one parameter and read-only annotations, the description covers purpose, usage, and error handling. However, it omits any description of the return payload (no output schema exists), and includes extraneous parameter guidance that detracts from completeness. The irrelevant tail leaves the agent uncertain about actual inputs, so completeness is partial.

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 is 100% covered with 'Array of usernames to search for', which is clear. However, the description references 'project_id'/'group_id' and 'pagination fields' that do not exist in the input schema, introducing misleading information. This actively confuses the agent rather than adding value, so despite high schema coverage the description detracts.

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 ('Get GitLab user details by usernames') and the specific resource type. It differentiates from discovery tools by explicitly directing users to 'list or search tools' when they need to discover multiple resources, which distinguishes this targeted lookup from sibling search/list tools.

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?

Provides explicit when-to-use guidance ('Use this for a known resource or result') and when-not-to-use ('choose the corresponding list or search tool when you need to discover multiple resources'). It also instructs on using identifiers and pagination fields exactly as documented, giving clear operational direction.

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