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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description still adds non-obvious behavior beyond the annotations: an unrecognized metric returns the list of known metrics instead of erroring. It doesn't describe the shape of the explanation payload, but nothing contradicts the annotations.

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?

Front-loaded with purpose, then the metric list, then the unknown-metric fallback, then the required arg. Efficient overall; the trailing 'REQUIRED arguments: metric' heading is mildly redundant with the schema's required array.

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 one-parameter, read-only explainer with no output schema, the description says what the answer contains (meaning, formula, caveats) and how invalid input resolves, which is enough for an agent to call it correctly. Only a hint at the actual return structure is missing, which is a minor gap.

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 description coverage is 100% and the single parameter's schema already documents examples and case/separator-insensitivity. The description reinforces this with a longer example set but contributes no additional syntax or matching rules beyond the schema, so the baseline of 3 applies.

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 verb+resource ('Explain a Levels.fyi compensation metric or concept') plus the exact output content (meaning, formula, caveats), and enumerates concrete metric examples like 'TC', 'vesting', 'sign_on'. That scope cleanly separates it from lookup siblings such as get-vesting-schedules or get-domain-knowledge.

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?

Makes the usage case explicit — call this to resolve what a metric means — and adds a concrete fallback path: 'Pass an unknown metric to get the list of known ones.' It doesn't explicitly name alternatives like get-domain-knowledge for broader concepts, so there is no stated exclusion, but the context is clear.

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