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

readOnlyHint=true already covers the safety profile, and the description adds real value on top by naming the fields returned (preferences, notification settings, schedule, deviceId) and mapping to GET /users/{id}. It omits error behavior for unknown ids and any auth/rate-limit notes.

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?

Two short sentences, zero filler, with the return-shape information front-loaded ahead of the endpoint mapping.

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 enumerated return fields do the necessary work of telling the agent what comes back, and the required vs optional params are handled by the schema. Only failure semantics (unknown user id) and the include_avatar side effect are left unaddressed.

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 description coverage is 100%, so both user_id and include_avatar are already documented by the schema. The description adds nothing about include_avatar's effect or whether the avatar is otherwise omitted, so the baseline 3 applies.

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?

States a specific verb and resource plus the identifier semantics ('Get one user by id') and enumerates the payload fields, which cleanly distinguishes it from the sibling rinkel_list_users. It stops short of naming the sibling explicitly, so it is clear but not maximally differentiated.

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?

Usage is only implied: the agent must already hold a user_id. There is no guidance such as 'use rinkel_list_users first to resolve an id' and no statement of when not to use it.

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