whoami

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

The description says 'Show', implying a read-only operation, but annotations declare readOnlyHint=false. This directly contradicts the annotations. Additionally, idempotentHint=false for an identity query is misleading, and no extra behavioral context is provided.

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 sentences, front-loaded with the core purpose followed by usage guidance. No wasted words, and the structure is optimal for a simple tool.

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?

Given the tool's complexity (0 params, no output schema) and the clear purpose, the description is complete enough. It tells the agent what it does and when to call it.

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 score is 4. The description does not need to add parameter semantics, and the schema coverage is 100% (though 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 uses a specific verb 'Show' and a specific resource 'this session's actor identity and effective project scope'. It clearly distinguishes from siblings like agent_status or agent_list, which concern other agents, not the current session.

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?

It explicitly states 'Call this first in a new session', giving clear context for when to use it. However, it does not mention when not to use it or name any alternative tools, so it falls short of a 5.

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