whoami

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

With no annotations provided, the description carries the behavioral burden. It clearly states what is returned (identity and effective grants) and adds useful context about how the result affects interpretation of other queries. It does not specify output format or error behavior, but for a zero-parameter introspection tool this is sufficient.

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 brief and front-loaded: the core purpose appears in the first sentence, and the usage guidance is a compact second paragraph. Every sentence contributes meaning with no redundancy.

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 zero-parameter, no-output-schema tool, the description fully covers what the tool does, why to call it first, and how the result should inform subsequent actions. There are no missing pieces that would prevent an agent from selecting or invoking it correctly.

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 tool has zero parameters, so the baseline is 4. The description adds no parameter-level detail, but none is needed because the input schema is already complete and empty.

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 opens with a specific verb ('Return') and the exact resource: the server's acting identity and effective grants. This clearly distinguishes it from sibling tools like list_controls or list_findings, which operate on different resources.

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 explicitly says 'Use this first' and explains why: it establishes scope for business units and sensitivity levels and helps interpret empty results. It does not name alternatives or exclusions, but given the tool's bootstrap role, that guidance is sufficient.

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