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

Annotations already declare readOnlyHint=true and openWorldHint=false, so 'Read-only, no charge' is partly redundant, but the description adds genuinely new context with 'illustrative estimate, not a diagnosis' — an important limitation the agent should relay. It also signals the output includes an external link to a browser tool, useful for a zero-param informational call; no contradiction with openWorldHint=false since the tool only surfaces a URL rather than fetching from the open world.

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 short sentences, front-loaded with the core purpose and followed by the key caveat. Nothing repeats the name or title verbatim and every clause (limits, link, free, not a diagnosis) carries information the agent would otherwise lack.

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 an output schema present, the description need not explain return values, and it covers purpose, cost, safety profile, and the critical 'not a diagnosis' framing. The only missing element is explicit guidance on when to invoke it versus list_styles, which keeps it just short of complete.

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 and the baseline is 4. The description correctly presents this as a parameterless lookup by framing it as a single explanatory response.

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 states a specific verb ('Explain') and a precise resource ('what the BaldFade Norwood Hairline Self-Check does and its limits'), plus the deliverable (a link to the browser tool). An agent can tell instantly that this is an informational lookup, not an action, and it does not overlap the sibling list_styles.

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 implied rather than stated: an agent can infer this is the tool to call when a user asks about the Norwood self-check. There is no explicit 'call this when...' or 'do not call for...' guidance, and the single sibling (list_styles) is never referenced to route the agent between them.

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