whoami

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

The description implies a read-only operation by stating it reports identity and grants, but it does not explicitly declare the tool as non-mutating or safe. Since no annotations are provided, the description carries the full burden and falls short of full transparency.

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 concise, using only three sentences to convey purpose and usage. It is well-structured with no redundant information, earning a perfect score for efficiency.

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 tool with no parameters and a simple purpose, the description fully covers what an agent needs to know: what it returns, when to use it, and its universal availability. The output schema exists, so no further explanation of return values is required.

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, and the schema coverage is 100% by default. There is no additional parameter information needed, and the description correctly omits any parameter details, making it perfectly appropriate.

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?

Clearly states the tool returns the current identity and grants, which is specific and distinct from sibling tools like find_customer or open_ticket. The phrase 'identity and grants' unambiguously describes the resource being queried.

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?

Provides explicit guidance on when to use the tool—when debugging why another tool fails, to check which token is being used. Also notes it is present in every deployment, giving context for availability.

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