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

With no annotations provided, the description fully shoulders the transparency burden. It discloses the dual challenge mechanism, the ALIVE/HOLLOW/DEAD classification, the cryptographic signature check, auth behavior verification, and the Ed25519-signed verdict, plus pricing and tier. This is exceptionally transparent.

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 longer than minimal but well-structured and front-loaded with the core purpose. Each sentence adds distinct value—from the challenge mechanism to the verdict signing to pricing. No redundancy or fluff.

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?

Considering the tool's complexity (multiple checks, output categories), the description is quite complete. It explains what inputs are accepted, what outputs to expect (ALIVE/HOLLOW/DEAD), additional checks, and cost. Minor gaps like error handling or timeout behavior prevent a perfect score.

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 input schema's parameter description already covers the allowed target formats (A2A endpoint, agent-card URL, or base origin) at 100% coverage. The tool description adds little beyond restating these formats, so the schema carries the meaning. Baseline 3 is appropriate.

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 tool as a 'liveness + authenticity oracle' that verifies A2A agents. It specifies the exact action (sends challenge messages, checks signature and auth) and distinguishes itself from sibling verification tools like onyx_attestation_verify or onyx_signature_guard by covering behavioral liveness testing.

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 an explicit use case: 'Use before trusting or transacting with any agent a registry lists as healthy.' While this gives clear when-to-use context, it does not mention when-not-to-use or alternative tools, so it falls short of a perfect 5.

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