lookup_user

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

The readOnlyHint annotation already signals a safe read operation, lowering the bar. However, the description adds no behavioral context beyond the annotation: it does not mention pagination behavior, substring matching, field selection semantics, or anything about what the search returns. The schema covers some of this indirectly, but the description itself contributes no transparency beyond the annotation.

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, front-loaded sentence with no filler. Every word contributes to the core purpose, and it is easy to parse 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 simple search tool with a fully described schema, the description is largely sufficient. The main gap is the absence of guidance on when this tool should be preferred over sibling user-related tools, but the basic call shape and parameter meaning are fully covered by the schema.

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 input schema has complete descriptions for all four parameters, including the special behavior of 'fields' replacing defaults. The description does not need to add parameter details; baseline 3 is appropriate because the schema carries the weight.

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 uses a specific verb ('Search') and resource ('RT users') with explicit search criteria ('by name or email address'). It clearly distinguishes this tool from siblings like get_current_user or list_group_members, which serve different user-related purposes.

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 no guidance about when to use this tool versus alternatives such as list_group_members or get_current_user. It implies a simple user lookup by name or email, but does not state exclusions or preferred contexts.

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