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

Annotations already declare readOnlyHint=true, so the safe read-only nature is covered. The description adds some useful context by listing the fields returned (email, phone, custom properties), but it doesn't disclose error behavior, auth needs, or whether a missing user returns null or an error. It adds value but not rich behavioral context.

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 sentence that states the action, the target resource, the key identifier, and the expected output fields. There is no redundancy or filler, and the most important information is front-loaded.

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 one-parameter read-only lookup with no output schema, the description is largely sufficient: it names the input and the output content. It is slightly incomplete because it does not address error/not-found behavior or how this differs from related profile/preference retrieval tools, but these are minor for this tool's complexity.

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 already documents the only parameter, user_id, with 'The user ID to look up,' covering 100% of parameters. The description's 'by their ID' adds no meaningful semantics beyond the schema, so the baseline of 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?

The description uses a clear verb-resource pair: 'Get a user profile by their ID,' and adds what the result contains (email, phone, custom properties). However, it does not explicitly distinguish itself from the many other get_* siblings, relying mostly on the tool name for differentiation.

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?

No when-to-use guidance is provided. The description does not mention when to prefer this tool over alternatives like get_user_preferences, get_user_push_token, or list_tenant_users, nor does it state any exclusions or prerequisites.

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