Whoami

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

The annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is fully covered. The description usefully adds that the result spans identity plus plan and credit balance, but says nothing about auth assumptions or what happens if no account is connected.

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, no filler. The what-it-returns statement comes first and the when-to-use guidance second, which is the correct front-loading for a zero-arg 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?

An output schema exists, so return-value structure need not be explained. For a zero-parameter, read-only identity call with full annotation coverage, the description supplies everything an agent needs to decide and invoke.

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 zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The enumeration of returned fields gives a hint of what the call surfaces without needing input semantics.

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?

States a specific resource (the connected account) and enumerates exactly what is reported: email, workspace, role, plan, credit balance. None of the sibling tools (deck/project/task/brand-kit management) overlap with this identity lookup, so an agent can select it unambiguously.

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 second sentence gives clear triggering conditions: when the user asks which account is connected, what plan they're on, or how many credits remain. It does not name an alternative, but no sibling offers account or billing information, so there is little ambiguity to resolve.

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