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

Beyond the readOnly/idempotent annotations, it discloses the underlying data source, both EntryPoint versions, and the computed outputs including smart-account status, op count, success rate, and per-sponsor share. It also adds operational details like default/max days, pricing, free tier, and lack of API-key requirements.

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 front-loaded with the key question and concept, then moves through data sources, inputs, and pricing in a logical order. It is slightly redundant ('Required input: wallet' appears twice) and includes a generic disclaimer, so it is not perfectly tight.

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 an output schema present, the description does not need to enumerate return fields. It covers the tool's blind spot, data sources, inputs, defaults, output dimensions, and cost/authentication behavior, making it sufficient for an agent to invoke the tool correctly.

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?

The schema already describes both parameters with 100% coverage, and the description adds genuinely useful constraints such as days defaulting to 30 and maxing at 90, plus confirming wallet is required. This goes slightly beyond the schema without fully elaborating each parameter.

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 names the exact resource and analysis: it reads a wallet's UserOperationEvents across both EntryPoint v0.6 and v0.7 and determines whether gas is paid by the account itself or a paymaster. It also frames a precise question ('Who pays this wallet's gas?') and distinguishes itself from normal ETH-spend heuristics.

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?

It gives clear context for when to use the tool: to detect paymaster-sponsored gas that would be invisible to spend-based checks, and it states that wallet is required and days is optional. However, it does not explicitly name alternative sibling tools or describe when not to use it.

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