tools_http_header_checkerFree public API. Fetch a URL and return its response headers + security grade based on common security headers.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Full URL with scheme, e.g. https://example.com. |
| Name | Required | Description | Default |
|---|---|---|---|
| ok | Yes | Always true here; failures return an isError result instead. | |
| data | Yes |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": true,
+ "description": "Response headers and a security-header grade.",
+ "properties": {
+ "data": {
+ "additionalProperties": true,
+ "properties": {
+ "finalUrl": {
+ "description": "URL after following redirects.",
+ "type": "string"
+ },
+ "headers": {
+ "items": {
+ "additionalProperties": true,
+ "properties": {
+ "name": {
+ "type": "string"
+ },
+ "value": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "name",
+ "value"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "responseTimeMs": {
+ "type": "number"
+ },
+ "security": {
+ "additionalProperties": true,
+ "properties": {
+ "findings": {
+ "items": {
+ "additionalProperties": true,
+ "properties": {
+ "header": {
+ "type": "string"
+ },
+ "note": {
+ "type": "string"
+ },
+ "present": {
+ "type": "boolean"
+ },
+ "rating": {
+ "description": "good | warning | missing.",
+ "type": "string"
+ },
+ "value": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "header",
+ "present",
+ "rating",
+ "note"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "grade": {
+ "description": "A+ to F.",
+ "type": "string"
+ },
+ "score": {
+ "description": "0-100.",
+ "type": "number"
+ }
+ },
+ "required": [
+ "grade",
+ "score",
+ "findings"
+ ],
+ "type": "object"
+ },
+ "status": {
+ "type": "number"
+ },
+ "statusText": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "finalUrl",
+ "status",
+ "statusText",
+ "responseTimeMs",
+ "headers",
+ "security"
+ ],
+ "type": "object"
+ },
+ "ok": {
+ "description": "Always true here; failures return an isError result instead.",
+ "type": "boolean"
+ }
+ },
+ "required": [
+ "ok",
+ "data"
+ ],
+ "type": "object"
+}Does 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 only 'Free public API', which hints at public availability but says nothing about rate limits, auth, or redirect/timeout behavior for a network fetch.
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?
Two short sentences with no padding. The purpose clause is front-loaded enough, though leading with 'Free public API' precedes the more decision-relevant capability.
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?
An output schema exists, so return values need no explanation, and a single fully documented parameter is sufficient input detail. Only the missing sibling routing keeps it from being complete.
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 with 100% schema description coverage ('Full URL with scheme, e.g. https://example.com'), so the schema already does the work. The description adds no format, protocol, or validation detail beyond it.
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 (Fetch) and resource (URL), plus what it returns: response headers and a security grade derived from common security headers. That output shape distinguishes it from generic siblings like tools_website_status_checker, though it never names an alternative explicitly.
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?
There is no guidance on when to use this tool versus the many overlapping siblings (status checker, redirect checker, SSL check). An agent must infer the use case purely from the output description.
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.