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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the bar is lower. The description adds meaningful, non-redundant context by specifying what is returned (HTTP 402 body and header) and the edge-case behavior for paid/pending runs. This goes beyond the annotations 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 description is only two sentences and front-loads the core purpose. The first sentence states what the tool returns and the key constraint (no charge); the second covers an important edge case. Every sentence earns its place with zero fluff.

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?

The description explains the return payload and behavior for paid/pending runs, but it omits some context needed for correct use: it assumes the existence of a run, does not clarify runId semantics (only in schema as 'uuid'), and does not mention any required prerequisites like creating a run first. Given no output schema, the description carries more weight and could be more explicit about the full response format.

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 50%; only clientToken has a description. The tool description does not mention either parameter, so it adds no meaning for runId (which is bare in the schema). With half the parameters undocumented and no compensation in the description, an agent may struggle to understand what runId refers to beyond a UUID.

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 states a specific verb ('returns'), the resource ('existing HTTP 402 body and PAYMENT-REQUIRED header'), and a clear scope ('without a signature or charge'). It is easily distinguishable from siblings like get_receipt or poll_run, and the title reinforces the unsigned quote purpose.

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 clearly implies when to use this tool: when you need the current quote without initiating payment. The phrase 'without a signature or charge' and 'A paid/pending run returns its original state' provide clear context. However, it does not explicitly name alternatives or exclusions, such as 'use get_receipt after payment', so it stops short of the top tier.

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