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

Annotations only cover read-only/open-world safety, but the description adds material behavioral context the annotations cannot: the data source (NYISO MIS files), eastern time stamps, real-time-only market, and critically the cost model ($0.002 USDC per successful call via x402, failed calls not charged). The billing disclosure is exactly the kind of behavior an agent must know before invoking.

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?

A single dense but front-loaded block: purpose first, then data detail, then market scope, then billing. Nearly every clause carries information, though the zone enumeration and component list make it longer than strictly necessary for a one-parameter tool.

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 needn't document return structure, yet it still explains the price components and the per-zone daily average included. Combined with annotations for safety and explicit billing terms, an agent has everything needed to decide and call 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?

Schema coverage is 100% — the single optional 'zone' parameter already has examples (N.Y.C., LONGIL, CAPITL, WEST). The description echoes the same zone names and adds the useful fact that there are 15 zones/interfaces, but it does not explain what omitting the parameter returns, so it only marginally exceeds the schema.

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 a specific verb+resource (NYISO real-time zonal electricity LBMP prices) and its exact granularity (latest 5-minute values for 15 zones and interfaces), plus the components returned (loss and congestion). It explicitly excludes the day-ahead market, which cleanly separates it from any day-ahead sibling and from the other ISO tools.

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 establishes clear use context: real-time market only, sourced from NYISO public MIS files, eastern timestamps. The exclusion 'day-ahead not included' functions as a when-not signal, though it does not name an alternative tool to use for day-ahead prices.

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