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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data rather than the description. The description adds only the HTTP route mapping and says nothing about auth requirements, 404/not-found behavior, or error shape for an invalid id; with annotations carrying the safety signal, a 3 is appropriate.

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, front-loaded sentences with no filler; the purpose leads and the endpoint detail follows. The route mapping is marginally useful but borders on redundancy for an agent that never sees the raw HTTP layer.

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 one-parameter read-only getter with annotations covering safety and no output schema to explain, the definition is sufficient to call correctly. Only the error/not-found behavior and the id's provenance are left unstated, which are minor gaps here.

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% with a single documented parameter, so the schema already carries the semantics. The description restates 'by id' without adding format, source, or sourcing guidance (e.g., where to obtain a user id).

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 ('Get a single user by id') and adds the underlying REST route, so an agent knows exactly what it returns. It does not, however, name or contrast itself with the nearby list_users sibling, which is the main ambiguity a caller faces.

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 by 'by id' – an agent infers it needs a known user id rather than a listing operation. There is no explicit when-to-use, when-not-to-use, or pointer to list_users for the no-id case.

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