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

The description adds real information the annotations don't carry: a concrete price point (0.004 USDC), determinism, evidence-boundedness, and that results are cryptographically signed. This complements readOnly/idempotent hints well. It stops short of explaining what 'evidence-bounded' means operationally or what the caller must supply as evidence, so it is not a 5.

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?

Three terse fragments separated by semicolons, with a stray leading semicolon artifact; the purpose is front-loaded but the pricing and determinism claims are compressed to the point of being cryptic. Short is good, but this is under-specified rather than efficiently worded.

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?

An output schema exists, so return values need not be described. However, the input schema is property-less and only demonstrated via example, so the description should have explained the factors/evidence structure and what constitutes acceptable evidence for a 'deterministic, evidence-bounded' score. The safety profile is covered by annotations, but input construction guidance is missing.

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?

Parameter count is technically 0, which would normally warrant a 4, but the schema has no declared properties and instead relies on an example payload containing factors (name, weight, probability, evidence_refs) and amount_atomic. The description mentions 'evidence-supported' only in passing and never explains the factors/weight/probability structure an agent must actually construct. Because the schema is untyped rather than self-documenting, the description should compensate and does not.

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 says it will "estimate evidence-supported loss probability," which is a specific verb and outcome, but it never mentions transactions, scoring, or how it differs from the many payment/transaction siblings (transaction_assurance, payment_preflight, duplicate_charge_detector). The noun phrase 'loss probability' is only loosely connected to the tool name 'transaction_risk_score,' so an agent must infer the mapping.

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?

There is no statement of when to call this versus the 28 sibling tools; 'without selling insurance or assuming liability' is a legal disclaimer, not a routing rule. With so many overlapping payment-risk siblings, the absence of any 'use this instead of X when Y' guidance is a real gap.

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