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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), but the description adds genuinely new behavioral context: a 'guarded live v2 challenge', 'bounded logs' for the seven-day window, and the fact that unavailable checks are reported back. That last point is a meaningful disclosure about partial-failure handling.

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?

A single dense sentence front-loads the trigger ('Use when...') followed by the enumeration of checks and the verdict return. Every clause carries information, though the enumeration is long enough to be slightly dense on first read.

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 no output schema, the description compensates by naming the verdict values (no_issues_found, caution, avoid) and noting that unavailable checks are returned. That is enough for an agent to know what comes back and how to act on it; only failure/latency or pricing behavior for the paid call is left implicit.

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 description coverage is 100%, with detailed per-parameter docs including the holder wallet discount and the optional payment payload. The description adds no parameter-level detail beyond what the schema already provides, so the baseline 3 applies.

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 and resource ('check an x402 seller before paying') and enumerates the concrete checks performed (Bazaar listings, payment terms, live v2 challenge, seven-day Base USDC inflow, cited red flags). An agent can distinguish it from general siblings like wallet_check, though it doesn't name the alternative explicitly.

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 'Use when an agent needs to check an x402 seller before paying' gives clear triggering context. It does not name when-not conditions or sibling alternatives (e.g., payment_verify vs. this pre-payment check), so it stops short of full routing guidance.

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