netdiag-mcp

tls_cert_check

Check the TLS certificate presented by a host:port to verify its subject, issuer, validity period, and SANs.

Instructions

Fetch the TLS certificate presented on host:port and report subject/issuer/validity/SANs.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "host": "<host>"
    },
    "name": "tls_cert_check"
  }
}

Input Schema

Name	Required	Description	Default
`host`	Yes
`port`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 30, 2026

TDQS

A3.7/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It honestly conveys that this is a read-only network fetch and lists the returned certificate aspects. It does not disclose edge behavior such as whether the cert chain is validated, what happens with expired/cinvalid certs, or failure modes, but for a simple fetch/report tool the disclosed behavior is reasonably transparent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single, front-loaded sentence states the operation first and then the output scope. There is no filler or repetition, every phrase earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has only two parameters, one of which has a default, and an output schema exists, so the description does not need to enumerate return values. It covers the core operation but lacks explicit usage guidance and parameter conventions, making it minimally viable rather than richly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It does clarify that the tool connects to 'host:port', giving meaning to both parameters. However, it does not explain host format, port range, or relationship to the default port, leaving most parameter detail to the schema's names and default.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Fetch'), a concrete resource ('the TLS certificate presented on host:port'), and the reported fields (subject/issuer/validity/SANs). This clearly distinguishes the tool from sibling network checks like tcp_port_check or dns_lookup.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage: call this when you need TLS certificate details rather than just connectivity or DNS information. However, it does not explicitly state when not to use it or name an alternative tool, so the guidance is implicit rather than explicit.

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

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