Decrypt or encode data with a known XOR key, or brute-force single-byte keys ranked by plausibility for CTF and pentest analysis.
XOR with a known key, or (key empty) brute-force single-byte keys ranked by plausibility.
| Name | Required | Description | Default |
|---|---|---|---|
| key | No | ||
| data | Yes | ||
| key_format | No | text | |
| input_format | No | text |
Changes observed during successful MCP inspections.
v0.4.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavior burden. It does disclose two behaviors an agent could not guess: the empty-key brute-force fallback and that candidates come back 'ranked by plausibility' — useful output-shaping context. It omits limits (key length ceiling, data size), error behavior, and any output shape, so it is only partially transparent.
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?
One sentence, front-loaded with the primary operation and immediately followed by the alternate mode condition. Every clause carries information; nothing is padded.
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?
No output schema and no annotations mean the description has to be self-sufficient. It covers mode switching but leaves two format parameters and the brute-force result format unexplained, which is not enough for an agent to invoke this correctly on non-text inputs.
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?
Schema description coverage is 0% with 4 bare-titled parameters, so the description must compensate. It only explains 'key' (empty means brute-force); key_format and input_format are left completely undefined — an agent cannot tell whether they accept 'hex', 'base64', or 'raw', and 'text' defaults give no hint.
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?
Names a specific operation (XOR) plus a second mode (single-byte brute-force), with the trigger condition stated. It does not explicitly contrast itself with nearby siblings like pentest_ctf_cipher_brute or pentest_ctf_decode, so an agent must infer the distinction.
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 parenthetical '(key empty)' is a usable mode-selection rule, which is better than nothing. However there is no guidance on when to reach for this tool versus cipher_brute or decode, and no statement of preconditions or limits.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.