CyberChef MCP Server

cyberchef_categories

Read-onlyIdempotent

Browse CyberChef operation categories with counts and examples to discover available data-transformation tools before listing individual operations.

Instructions

List CyberChef's operation categories with counts and examples. Start here to browse what this server can do, then use cyberchef_list_operations.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "cyberchef_categories"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`usage`	Yes
`categories`	Yes
`analysisTools`	No
`totalOperations`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv4.1.0Sep 12, 2026

addedOutput schema / properties / analysisTools

Added value: +{
+  "properties": {
+    "count": {
+      "type": "number"
+    },
+    "description": {
+      "type": "string"
+    },
+    "tools": {
+      "items": {
+        "properties": {
+          "title": {
+            "type": "string"
+          },
+          "tool": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "tool",
+          "title"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "usage": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "count",
+    "description",
+    "tools",
+    "usage"
+  ],
+  "type": "object"
+}

First observedv3.6.0Sep 4, 2026

TDQS

A4.5/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered without the description. The description adds only that results include counts and examples, which is mild extra value; with an output schema present there is little more it needs to disclose.

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?

Two short sentences, front-loaded with the action and resource, followed by the routing hint. Every clause earns its place with no filler.

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

Completeness5/5

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

For a zero-parameter, read-only browsing tool with an output schema and full annotation coverage, the description supplies everything an agent needs: what it returns and where it fits in the workflow.

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

Parameters4/5

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

The tool takes zero parameters, so there are no parameter semantics to explain; the baseline for a parameterless tool is 4. The description correctly implies no input is required.

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?

Specific verb ('List') plus resource ('CyberChef's operation categories') with added scope detail (counts and examples). It also names the sibling cyberchef_list_operations, letting an agent place it relative to the operation-listing tool without opening either schema.

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

Usage Guidelines5/5

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

Explicitly positions itself as the entry point ('Start here to browse what this server can do') and names the follow-up action with its tool ('then use cyberchef_list_operations'). This is unambiguous routing guidance, not inference.

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