whoami

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

No annotations exist, so the description carries the full burden, but the burden is light for a zero-argument identity probe. It discloses what is returned (user, workspace, plan) yet never states that it is a read-only, side-effect-free lookup with no auth beyond the key/session already in use. That omission keeps it at a minimum-viable 3.

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 front-loaded clause ('Who am I:') followed by the exact scope of the answer. Every word earns its place and there is no restatement of the title or name.

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?

With zero parameters and no output schema, the description usefully enumerates the three things returned (user, workspace, plan), which is exactly the detail an agent needs to decide whether this call answers its question. It could go one step further by noting the answer reflects the calling credential, but the gap is minor.

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 takes no parameters and the schema is trivially complete, so the baseline is 4. Nothing in the description is needed to explain inputs, and it correctly makes no attempt to document nonexistent parameters.

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 names a specific resource set: the user, workspace and plan behind the current key or session. That is unambiguous and distinguishes it from every sibling, which all deal with campaigns, mailboxes, domains or threads rather than credential identity. It would need a verb form (returns/resolves) to reach 5, but the intent is clear.

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?

Usage is only implied: an agent can infer it is the tool to call when it needs to know which account the credential belongs to. There is no explicit when-to-use, no prerequisites, and no statement that it is the cheap first call before other operations. Adequate but with a clear gap.

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