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

Annotations already declare readOnlyHint true, idempotentHint true, and destructiveHint false, so the safety profile is covered. The description adds useful behavioral context by clarifying that the tool 'Does not execute' and that the output is a signed x402 quote, which goes beyond the structured annotations.

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 description is one tight sentence plus a clarifying fragment. Every word contributes: it states the two modes, mentions the signed quote, and explicitly rules out execution. It is front-loaded with the primary action and contains no filler.

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 and zero parameter descriptions, the description is too thin for a tool with five parameters and nested objects. It does not explain how the two modes map to parameters, what a successful quote response looks like, or what conditions make the signed quote obtainable.

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 0%, and none of the five parameters (input, intent, operation, capability, idempotency_key) are explained. The description mentions 'capability' and 'public outcome,' which loosely maps to some parameters, but it does not explain how to construct input, intent, or operation, nor the role of idempotency_key.

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 uses specific verbs and resources: 'Inspect XGuard credit pricing for a capability' and 'obtain a signed x402 quote for a public outcome.' It also differentiates from the executing tool by stating 'Does not execute,' so an agent can tell it apart from siblings like xguard_execute.

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 description gives clear context: use this tool when you need credit pricing or a signed x402 quote, and it explicitly says the tool does not execute. It does not name sibling alternatives like xguard_execute directly, but the context is clear enough that an agent can infer when to choose this tool over execution tools.

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