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

Annotations already establish readOnly, idempotent, and non-destructive behavior, and the description adds meaningful context: fail-closed semantics, deterministic results, evidence-bounded output, and signed results, plus an apparent 0.003 USDC cost. This goes beyond the structured fields without contradicting them.

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?

The text is short and front-loaded with the core failure behavior, but the remaining clauses are sentence fragments; '0.003 USDC' is ambiguous between a cost and a threshold, and the list grammar is slightly off. It earns points for brevity but loses polish.

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 zero-parameter policy tool with an output schema and safety annotations, the description covers the core decision, determinism, and signed evidence. It is incomplete on when to choose this tool over related guards and on what exact input object the tool expects, which matters because the schema is intentionally open.

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?

There are zero documented parameters and the input schema is an open object, so the description must carry the semantic weight; it names the relevant conceptual inputs (delegated authority, per-call limit, remaining budget). It still doesn't provide exact keys or value formats, but with no schema-defined parameters this is a reasonable baseline-4 case.

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 first clause names the resource (delegated spend) and the core behavior (fail closed when delegated authority, per-call limit, or remaining budget is insufficient), so an agent can tell this is an authorization/policy gate. It does not explicitly state a success-path action or differentiate itself from the many guard-style sibling tools, which keeps it from a 5.

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 'use when' or 'instead of' guidance, and none of the many sibling guard tools are named as alternatives. The only usage cue is the failure condition, which tells an agent when the tool would block, not when it should be called.

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