Check if an email/domain is disposable

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

With no annotations, the description carries the full disclosure burden. It usefully reveals the data source and freshness (~160k-domain MIT blacklist, auto-refreshed weekly), but omits what a non-match means, how unknowns are treated, and any rate or coverage limits.

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 tight sentences with the capability front-loaded and the accepted input form immediately after. Every clause earns its place and there is no padding.

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?

There is no output schema, so the description should indicate what the check returns (boolean, matched provider, confidence), but it does not. For a simple one-parameter lookup this is a modest rather than severe 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 already documents 'Email or bare domain' with examples. The description's 'Accepts a full email or a bare domain' restates that rather than adding format, normalization, or subdomain-handling detail, so the baseline 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 and resource ('Detects throwaway / temporary email providers'), which is clearly narrower than siblings like check_mx or verify_bulk. It does not explicitly distinguish itself from check_email, which could plausibly overlap, so it falls short of a 5.

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 says what the tool accepts but never states when to use it versus check_email, verify_bulk, or check_mx. No prerequisites, exclusions, or routing conditions are given, leaving usage entirely to inference.

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