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

With no annotations, the description carries the full behavioral burden. It states the failure result for wrong password or identity, imposes a ciphertext size bound, lists the successful outputs, and describes the cryptographic relationship between inputs. This goes well beyond a bare operation name, though it does not cover every edge case such as invalid ciphertext structure.

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 information-dense and front-loaded with the operation type, but it carries a redundant duplicate '[sm9_ibc] [sm9_ibc]' prefix and is a long single run-on sentence. It is concise overall, but the waste and lack of structure prevent a higher score.

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 crypto tool with no output schema and no annotations, the description is quite complete: it covers inputs, expected key origin, consistency constraints, ciphertext size, outputs, and a known error string. The main gap is that the schema marks all parameters optional while the description implies all are needed, leaving required-ness ambiguous.

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 meaningful cross-parameter context: user_private_key_in_pem must be an SM9ExtractKey output, the password must match extraction, the identity must match encryption, and cipher_data_in_hex is DER ciphertext limited to 367 bytes. This adds semantics the schema does not express.

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 identifies the operation as SM9 identity decryption, states the receiver role, and names all required inputs and outputs. The verb '解密' distinguishes it from sibling tools like sm9_encryption and sm9_sign.

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?

It gives explicit usage context: the receiver uses the KGC-issued user key, the key must come from SM9ExtractKey with key_kind=Enc, the password must match extraction, and the identity must match the encryption. It does not explicitly name when not to use it or enumerate alternatives, so it stops short of a 5.

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