Resolve a ~handle

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety is covered. The description adds valuable behavioral context beyond annotations: 'Never returns PII', 'Free L0, no authentication required', and the specific return categories (canonical handle, kind, addressability).

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 compact and front-loaded: purpose comes first, followed by usage guidance, return summary, and caveats. Every sentence contributes useful information without redundancy or boilerplate.

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 single-parameter, read-only tool, the description covers what it returns, when to call it, how it differs from alternatives, cost tier, authentication, and privacy behavior. No output schema exists, but the stated return fields are sufficient for an agent to invoke and interpret the result correctly.

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?

Schema coverage is 100%, and the schema already thoroughly documents the parameter, including accepted formats, case-insensitivity, and max length. The description adds minimal extra semantic value beyond reinforcing what a ~handle is, so baseline 3 is 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?

The description clearly states the tool resolves a ~handle to its canonical form and kind, naming a specific verb, resource, and output. It distinguishes itself from identity verification by explicitly noting 'Never returns PII; use verify_identity for that.'

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 tells the agent when to use this tool: 'Use this as your first call when you have a handle and need to confirm it exists before calling other tools.' It also points to an alternative for PII needs, giving clear decision guidance.

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