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

With no annotations, the description carries the full burden of behavioral disclosure. It states the output fields (plain_data_in_hex, plain_length) and warns that a mismatch in cipher_format leads to failure. It also covers the condition for providing a password, which is useful behavioral context beyond a bare function signature.

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 highly structured with sections for parameters, output, and notes. It is concise, with no wasted words, and front-loads the purpose. Each line serves a distinct function, making it easy to scan.

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 4 parameters and no output schema, the description covers the essential aspects: purpose, parameter formats, output fields, and a critical failure condition. It is sufficient for an AI agent to invoke the tool correctly.

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 coverage is 100%, so the baseline is 3. The description adds value by emphasizing that cipher_format is mandatory ('必须指定'), clarifying that the key is in PEM format, and explaining when the password is required. These details go beyond the schema descriptions.

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 'SM2 私钥解密' (SM2 private key decryption), specifying the exact operation and resource. It distinguishes from siblings like sm2_encryption and sm2_sign by focusing on decryption with private key.

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?

Provides clear usage context: cipher_format must be specified and must match the encryption format, otherwise decryption fails. It also notes when the private key password is needed. However, it does not explicitly mention alternatives like sm2_encryption for the reverse operation, 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.