Check a URL's security headers, identify missing protections like HSTS, CSP, and X-Frame-Options, and receive a security grade.
Check security headers for a URL. Returns present and missing headers (HSTS, CSP, X-Frame-Options, etc.) with a security grade.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Full URL to check (e.g., "https://github.com") |
Changes observed during successful MCP inspections.
v1.4.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the description does not need to repeat those. It adds useful behavioral detail about the output (present/missing headers, security grade), which helps the agent anticipate results. It does not mention network behavior or rate limits, but that is not essential given the annotations.
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 is a single, information-dense sentence with no wasted words. The purpose is front-loaded, and the return details are given in the second clause. It is appropriately concise for a simple tool.
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 single-parameter read-only tool with no output schema, the description fully explains what the tool does and what it returns. The annotations cover safety, and the schema covers the parameter. Nothing an agent needs to invoke it correctly is missing.
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 covers the single parameter (url) with a clear description and example. The tool description does not add any extra meaning beyond the schema, so the baseline of 3 is appropriate. There is no need to compensate for missing schema coverage since coverage is 100%.
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 states a specific verb ('Check') and resource ('security headers for a URL'), and explicitly mentions what is returned (present/missing headers, security grade). This clearly distinguishes it from sibling tools like check_ssl, check_cors, and check_mixed_content, which target different aspects of web security.
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 provides clear context on what the tool does, so an agent can infer when to use it. However, it does not explicitly mention alternatives or state conditions when this tool is NOT appropriate (e.g., for SSL checks or CORS issues). Since it clearly scopes to security headers, this is adequate but not fully explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.