email_validate

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

With no annotations, the description carries the full burden and does disclose useful non-schema traits: the return contract (is_valid boolean plus granular checks), per-call cost ($0.0035 USDC), and p99 latency (400ms). It does not cover auth/payment mechanics for the paid call, rate limits, or error behavior, so it falls short of fully transparent.

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?

Single dense paragraph, front-loaded with the purpose, then returns, then usage, then cost/latency — a sensible order. The leading 'Email Validation —' restates the tool name and is the only mildly wasted text.

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?

No output schema exists, and the description correctly compensates by naming the return fields. Cost and latency round out the picture for a simple one-parameter tool. The main omission is disambiguation from email_verify.

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?

One parameter at 100% schema description coverage, so the schema already defines 'email' fully. The description adds no format, normalization, or edge-case guidance beyond what the schema states, matching the baseline of 3.

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 and enumerates the four concrete checks performed (RFC 5322, MX lookup, disposable provider, role address) plus the return shape. However, it never addresses the near-identical sibling 'email_verify', so an agent cannot tell from the description alone which of the two to call.

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?

Gives a clear use case ('before storing or sending to email addresses to prevent bounces'), which is genuine context. But with a sibling literally named email_verify in the toolset, the absence of any when-to-use-this-vs-that guidance is a material gap.

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