verify_auth_request_cryptogram

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

With no annotations, the description carries the full burden and it does substantial work: it states the required E0 key type, that AES-128 E0 keys are rejected, that UnionPay needs boto3 >= 1.43.49 or fails client-side, and that ARPC generation is optional in the same call. It loses a point because the acronym 'APC' is used twice without being defined and the response/return behavior is not disclosed.

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 definition is front-loaded with purpose and usage, and the parameter examples are dense but valuable. It is slightly overweight: 'ISO 8583 field 55' appears twice with almost the same wording, and the unexplained 'APC' adds noise.

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 complex 6-parameter tool with nested objects, no output schema and no annotations, the description covers inputs and constraints well but never states what the API returns (verification outcome, generated ARPC hex). Without that, an agent cannot fully know how to consume the result, especially when auth_response_attributes is supplied.

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 0%, so the description fully compensates: every parameter is named with a purpose, key_identifier is typed as ARN/alias of an E0 key, derivation modes are enumerated, and session_key_derivation_attributes/auth_response_attributes get concrete JSON examples for each union member. This goes well beyond the bare schema.

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 leads with a precise verb and resource: 'Verifies an EMV Authorization Request Cryptogram (ARQC) and optionally generates an Authorization Response Cryptogram (ARPC) in the same call.' It also names the sibling generate_auth_request_cryptogram in the parameter notes, making the verification-vs-generation distinction discoverable.

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 opening sentence explicitly says when to call ('implementing EMV transaction authorization', 'generating an issuer ARPC response', 'validating EMV session key derivation'), which is a clear usage trigger. It does not provide the complementary when-not-to-use or direct alternative routing beyond the sibling mention, so it misses a perfect score.

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