Find email addresses for a domain via Hunter.io, optionally filtering by first and last name to target specific contacts.
Find email addresses for a domain using Hunter.io.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | ||
| api_key | No | ||
| last_name | No | ||
| first_name | No |
Changes observed during successful MCP inspections.
v0.1.5Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds that this hits an external provider (Hunter.io), but it omits credit consumption, API-key requirements, rate limits, and outcome when nothing is found — meaningful gaps for a paid third-party API.
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?
A single front-loaded sentence with no waste. Brevity is appropriate, though it is arguably under-specified rather than tight.
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 and no parameter documentation, plus an external paid API. The description does not say what a result looks like, how confidence/verification is expressed, or what happens on empty results — insufficient for an agent to call this confidently.
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 0% across four parameters. The description only implicitly covers 'domain' and says nothing about first_name/last_name filters (which change how results are targeted) or the api_key, so it does not compensate for the missing schema documentation.
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 (find) and resource (email addresses) scoped to a domain, and names the upstream provider. It is clear what the tool returns, though it does not explicitly distinguish itself from siblings hunter_verify_email or hunter_domain_info.
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?
No when/when-not guidance and no named alternatives. An agent must infer from the fragment 'for a domain' that this is a domain-based email discovery call rather than verification or enrichment.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.