crypto_symmetric

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

With no annotations, the description carries the burden and does disclose key derivation (SHA-256 from password, or direct key_hex) and output formats (base64 with iv/tag for GCM, iv only for CBC). However, it omits important behavioral details like GCM authentication, CBC's lack of authentication, IV reuse risks, and failure modes on decryption.

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 concise, with three sentences that front-load the purpose and then efficiently cover algorithm choices, key derivation, and output format. Every sentence adds value without redundancy.

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?

For a cryptographic tool with no output schema, the description provides essential invocation details: algorithm options, key input methods, and return format. It is complete enough for basic use, but lacks safety warnings and detailed error behavior that would fully round out the context.

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?

The description adds significant meaning beyond the schema by explaining the algorithm-specific output formats and the priority of key_hex over password. This helps agents understand the relationship between parameters, though action and iv_hex are not elaborated.

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 clearly states '对称加解密' (symmetric encryption/decryption) and specifies AES via node:crypto, making the tool's purpose unambiguous. It also lists exact algorithm options and output formats, distinguishing it from sibling tools like crypto_hash and encode_*.

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 provides clear context: this tool is for symmetric AES encryption/decryption. However, it does not explicitly mention when not to use it or name alternatives such as crypto_hash for hashing or encode_base64 for simple encoding, so it lacks explicit exclusions.

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