Get Microsoft 365 User

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe, idempotent read. The description adds the lookup key context (object id or userPrincipalName) but no additional behavioral traits such as return format or error behavior. With strong annotations, the bar is lower, and the description meets it without adding extra value.

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 a single sentence that is concise and directly conveys the essential information. No wasted words or repetition of the title.

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?

The tool is simple, with good annotations and no output schema. The description tells how to identify the user but does not mention what fields are returned or that 'select' can be used to choose specific properties. For a basic fetch operation, this is adequate 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?

The schema provides no descriptions for parameters (0% coverage), so the description must compensate. It clarifies that 'user' can be an object id or userPrincipalName, adding meaning to the first parameter. However, it does not explain the 'select' parameter (e.g., that it limits returned fields), leaving a gap for one of the two parameters.

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 'Fetch one user by object id or userPrincipalName,' using a specific verb and resource. It distinguishes this tool from siblings like list_users (which fetches multiple users) and get_group (which fetches a group). The scope is 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 provides clear context for when to use the tool: to retrieve a single user based on a specific identifier. It does not explicitly mention when not to use it or name alternatives, but the distinction from list_users is implied. This is sufficient for a straightforward read operation.

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