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doublegate

CyberChef MCP Server

by doublegate

cyberchef_cyclic_pattern

Read-onlyIdempotent

Generate De Bruijn cyclic patterns to identify buffer overflows, or find offset of a recovered register fragment within one. Supports pwntools-compatible generate/find modes with text or hex input.

Instructions

Generate a De Bruijn (cyclic) pattern, or find the offset of a fragment within one. Compatible with pwntools' cyclic/cyclic_find, so patterns and offsets are interchangeable with it. Use mode=find with the bytes recovered from a crashed register to get the overflow offset; hex input is interpreted as both big- and little-endian, because a register dump is usually reversed relative to memory.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
modeYesGenerate a pattern, or find an offset in one.
lengthNogenerate: how many bytes to produce. find: how long the pattern was.
alphabetNoSymbols to build from. The default matches pwntools.abcdefghijklmnopqrstuvwxyz
fragmentNofind: the bytes recovered, as text or hex (e.g. "aabc" or 0x63626161).
fragment_formatNofind: how to read `fragment`. Auto tries hex first, then text.Auto
subsequence_lengthNoBytes of uniqueness: 4 for 32-bit, 8 for 64-bit. Must match the pattern.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observedv3.6.0

TDQS

A4.7/5.0
Behavior5/5

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

Beyond the readOnly/idempotent annotations, it discloses a non-obvious parsing trap: 'hex input is interpreted as both big- and little-endian, because a register dump is usually reversed relative to memory.' It also states the interop guarantee with pwntools' cyclic/cyclic_find, which an agent could not infer from the schema or annotations.

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?

Three sentences with no filler: purpose, compatibility, and a concrete usage scenario. The most important scoping information is front-loaded in the first sentence, and every sentence earns its place.

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?

Despite having 6 parameters and no output schema, the description covers the core generate/find workflows, explains the compatibility contract, and warns about the endianness subtlety. Remaining details (defaults, bounds, enum values) are fully documented in the schema, so nothing an agent needs to invoke this correctly is missing.

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?

Schema coverage is 100% with per-parameter descriptions, defaults, and enums, so the baseline is 3. The description adds workflow wiring — mapping fragment bytes from a register dump and mode=find to the overflow offset — and the dual-endianness interpretation that modifies how `fragment` is parsed. These add meaning beyond the schema fields.

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 opens with a precise verb+resource statement: 'Generate a De Bruijn (cyclic) pattern, or find the offset of a fragment within one,' covering both modes explicitly. The pwntools compatibility mention further differentiates it from every sibling, none of which reference cyclic patterns or overflow offset finding.

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

Usage Guidelines4/5

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

It gives an explicit when-to-use instruction: 'Use mode=find with the bytes recovered from a crashed register to get the overflow offset,' tying the tool to a concrete exploit-development workflow. It does not name explicit alternatives or when-not-to-use conditions, but no sibling overlaps with this functionality, so the guidance is sufficient.

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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