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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely useful non-obvious semantics beyond that: private profiles return results indistinguishable from nonexistent ones, which tells an agent how to interpret a miss. It stops short of explaining auth requirements or return shape.

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, front-loaded with the resource and key, no filler. The only mark against it is that the 'Signed' phrasing is unclear and looks like template residue rather than intentional wording.

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 single-param read tool with full schema coverage and a complete annotation set, this is close to sufficient, and the private/nonexistent note covers the main edge case. However, with no output schema, the description says nothing about what the profile contains or whether authentication is required ('public Signed' is contradictory), leaving an agent unsure of the access model.

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 coverage is 100% with a single documented 'login' parameter, so the schema already carries the parameter meaning. The description's 'by login' only restates the schema and adds no format, casing, or matching guidance.

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 identifies the resource (a user profile) and the lookup key (login), so intent is inferable, but it is framed as a noun phrase rather than a clear verb, and the capitalized 'Signed' reads as garbled/truncated. It does nothing to distinguish itself from close siblings like get_person or whoami, which also return user/person data.

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?

There is no statement of when to use this tool versus whoami (current user) or get_person. The only routing-adjacent content is an error-behavior note about private profiles, which is not usage guidance. An agent must guess which of the several get_* profile tools applies.

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