Who am I

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

Annotations already declare readOnlyHint=true, and the description adds meaningful context about credential scope and how it affects page tools. This goes beyond the simple read-only flag, but it doesn't disclose potential edge cases or response details; still, for a simple whoami operation 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 two sentences long, with the core purpose front-loaded and no wasted words. Every sentence earns its place, and the structure is logical: first states what it does, then gives actionable usage advice.

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 read-only annotation, the description covers the essential context: what it identifies and how it relates to credential scope. It does not describe the return format, but given the low complexity and clear purpose, the description is nearly complete. A slight gap is the lack of explicit mention of response fields.

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 schema requires no explanation. The description correctly focuses on the tool's behavior rather than parameters. The baseline for 0 params is 4, and no additional parameter semantics are needed.

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 clearly states the tool's purpose with a specific verb and resource: 'Identify the authenticated AgentDocs user and credential scope.' It also distinguishes itself from sibling tools by positioning it as a preflight step ('Call this first'), which is unique among the listed page tools.

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 provides usage timing ('Call this first') and explains why it matters relative to space-scoped credentials. However, it does not explicitly mention when not to use it or name alternatives, though the context makes those clear. This is strong guidance but not a full 5.

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