Get user by id

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

With no annotations provided, the description must carry the behavioral transparency burden. 'Fetch' indicates a read-only operation, but the description does not add contextual details such as not-found behavior, authentication prerequisites, or return format. It provides the minimal expected behavioral signal without contradiction.

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, clear sentence with no wasted words. It is front-loaded with the action and resource, and directly followed by the identifying attribute, making it 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 2-parameter fetch tool without an output schema, the description and schema are enough for an agent to call it correctly. The only gap is not describing the exact return outcome when no user is found, but given the simplicity this is a minor omission.

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 covers both parameters with 100% description coverage ('Realm name' and 'Keycloak user id (UUID)'). The description only restates 'Keycloak id' without adding semantic depth, so a baseline score of 3 is appropriate since the schema does the heavy lifting.

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 ('Fetch'), a specific resource ('a single user representation'), and a precise selector ('by their Keycloak id'). This clearly differentiates it from sibling tools like list_users or count_users, which operate over collections.

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 clearly identifies the context: when you need one user by a Keycloak id, with no ambiguity about what kind of lookup. It implies the use case without naming alternatives, but the single-user scope and key-based identification make the intended usage sufficiently clear.

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