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

Annotations only declare readOnlyHint and openWorldHint, so the description adds real value by disclosing the cost ($0.02 / 20000 atomic USDC on Base) and the x402 payment flow — a critical, non-obvious behavioral constraint. It stops short of describing result count, latency, or failure/refund behavior on failed payment.

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?

Two sentences, no filler: capability and modes first, then cost and payment mechanism. Every clause earns its place and the key constraint (paid call) is not buried.

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 two-enum, read-only tool with no output schema, the description covers purpose, modes, and the payment prerequisite, which is what an agent needs before invoking. The one remaining gap is the shape of the returned screening results, which the absent output schema leaves undocumented.

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% with both parameters as fully described enums, so the schema carries the semantics. The description restates the same six scan values and the stocks/crypto split without adding format, defaulting, or combination rules (e.g., whether market affects scan semantics). 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?

States a specific verb (scan) and resource (stocks or crypto) and enumerates the six concrete screening modes, so the agent knows exactly what capability this is. Sibling tools are unrelated domains, so no differentiation is required, but the description never says what the scan produces (symbols, prices, ranks).

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?

Usage is only implied by the enumerated scan types; there is no explicit statement of when to pick this over alternatives (there are none among siblings) or what preconditions apply beyond payment. The pricing/payment sentence gives practical context but not selection guidance.

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