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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: 1-hour caching with <5ms hits, $0.01 pricing, first-5-free trial, failed calls never charged, and a payment-required quote flow with top-up link and USDC addresses. This is exactly the behavioral depth annotations cannot carry.

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?

Header-based structure is front-loaded and easy to scan. However, the free-trial and pricing facts are restated across the PARAMETER INTERACTIONS and Pricing sections, adding mild redundancy to an already long description.

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?

With an output schema present and annotations covering the safety profile, the description need not explain return values; it instead supplies pricing, caching, and payment-recovery flow. Everything an agent needs to call and pay for this tool correctly is 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 the baseline is 3, but the description adds cross-parameter interaction rules: omit agent_id/tx_hash during the 5 free calls, or supply agd_pass_/tx_hash for paid execution. That interaction logic meaningfully exceeds the per-field schema text.

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 (Inspects) and enumerates the exact outputs: IPv4/IPv6 DNS resolution, TLS certificate issuer/expiry, and HTTP security grade. It names the sibling tool get_agent_wallet_status, so an agent can distinguish this recon tool from the wallet-status tool without opening a 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?

Explicit WHEN TO USE and WHEN NOT TO USE sections, plus a named alternative (get_agent_wallet_status) for quota checks. The exclusions ('unrelated domains or binary media') and the paid-vs-free routing condition are all stated, leaving nothing to inference.

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