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

With no annotations, the description carries the full burden and does so richly: it discloses per-call cost (0.005 USDC via x402), the alternative ARCGATE-KEY header payment path where payment goes in params._meta, result ordering (agentId ascending), pagination via nextAfter, error behavior, and the semantic caveat that declarations are the agent's own claims. This is exactly the behavioral context an agent needs before calling.

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?

Bullet structure with Cost/Inputs/Returns/Errors/Next is well front-loaded and scannable. However, the cost is stated twice (the Cost bullet and the trailing paragraph), which is redundant text that doesn't earn its place.

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 7-parameter, no-annotation, no-output-schema tool, the description covers return shape (page of agents by agentId ascending with on-chain facts and registration declarations), pagination, errors and payment. It could say more about the fields inside each agent record, but the essentials for correct invocation are present.

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 every parameter is already documented in the schema, including the AND semantics ('every one, not any'). The description largely restates inputs rather than adding syntax or format meaning beyond what the schema provides, so the baseline of 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?

States a specific verb (lists), resource (agents in Arc's ERC-8004 IdentityRegistry) and a precise scope (those matching their registration-file declarations). This clearly separates it from the sibling agentProfile (single-agent read), so an agent can route without opening either schema.

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 'Next' section routes the agent to agentProfile for a single agent's checks and feedback, and the Errors section explains the 404 unknown_chain case. It also clarifies that feedback never orders or filters results, implying this tool searches on declarations, not reputation. It stops short of an explicit when-not-to-use statement.

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