cyberchef_vigenere_break

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

The description goes far beyond the readOnly/idempotent annotations by revealing the algorithm's internal decision logic: the index of coincidence is a filter, not a judge; multiple key lengths are shortlisted; and trigram scoring makes the final decision. It also discloses failure behavior and measured accuracy ('Exact key in 9 of 10 measured cases, and it reported its own failure on the tenth'), which is valuable transparency.

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 front-loaded with the core purpose and then provides dense, useful technical detail without any filler. Every sentence earns its place: purpose, differentiation, algorithm rationale, failure behavior, and measured reliability. It is detailed but still appropriately sized for a complex cryptanalysis 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?

Given no output schema, the description compensates by describing key recovery, per-position runners-up, plaintext scoring, and failure signaling. The schema fully documents inputs and preview behavior. Together, they give an agent enough context to select the tool, set parameters, and interpret the result appropriately.

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 100%, so all four parameters already carry clear meanings. The description adds algorithm-level context about key-length search behavior, but it does not add new parameter-level semantics beyond what the schema provides. Baseline 3 is appropriate because the schema does the heavy lifting.

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 opens with a specific verb and resource: 'Recover a Vigenere key from ciphertext alone.' It immediately distinguishes this tool from `Vigenère Decode`, which requires the key, and states that no other operation finds one. This makes the tool's unique role clear even among many sibling tools.

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 explicitly identifies the condition for use — ciphertext-only Vigenere key recovery — and contrasts it with the alternative, `Vigenère Decode`, which cannot be used without a key. It also clarifies the algorithm's intent and what the tool is designed to avoid, giving an agent clear guidance on when this tool is appropriate.

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