Free public API. Check the TLS certificate of any public hostname. Returns issuer, subject, validity dates, days until expiry, full chain, cipher, protocol, and SAN list. No Bearer required.
| Name | Required | Description | Default |
|---|---|---|---|
| host | Yes | Hostname to check. Optionally with port, e.g. example.com:443. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive traits. The description adds 'Free public API' and 'No Bearer required', disclosing authentication needs, and enumerates return data (issuer, subject, validity dates, etc.), which is valuable since no output schema exists.
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?
The description consists of two sentences, front-loaded with the main action, followed by return fields and an authentication note. Every part adds value, and there is no unnecessary repetition.
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 simple one-parameter tool with no output schema, the description covers purpose, return fields, and authentication. It could mention error handling for invalid hosts, but the annotations and schema provide sufficient context for typical use.
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 schema already provides a complete description of the host parameter, including the optional port example. The tool description does not add additional parameter-level meaning beyond confirming hostname scope. With 100% schema coverage, the baseline score of 3 is appropriate.
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 clearly states the tool checks TLS certificates of public hostnames, using the specific verb 'Check' and resource 'TLS certificate'. It lists return values, which distinguishes it from sibling DNS and web tools.
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 implies usage for SSL/TLS certificate checks and notes it's a free public API with no Bearer required, providing clear context. It does not explicitly mention alternatives or exclusions, but the purpose is unambiguous compared to sibling tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Multiple tools operate in the same DNS/domain space, e.g., generic DNS record lookup overlaps with specific CNAME, TXT, SPF, DKIM, and DMARC lookups. Website status checker also overlaps with SSL check and redirect checker, though descriptions clarify their distinct purposes.
All tool names follow a consistent snake_case pattern with a 'tools_' prefix and an action word at the end (lookup, checker, check, finder). This makes the naming highly predictable and uniform.
16 tools is slightly above the ideal 3-15 range, but the domain intelligence scope is broad enough that each tool addresses a specific need without feeling bloated. The count is reasonable for a comprehensive domain/DNS toolkit.
The tool set covers a wide range of domain-related functionality: DNS records, email authentication (SPF, DKIM, DMARC), SSL/TLS, HTTP headers, redirects, WHOIS, availability, subdomain enumeration, and website status. No obvious critical gaps exist for its apparent purpose.
