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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false. The description adds contextual behavior: real-time, for today, specific output details (carbon intensity per interval, marginal CO2). No contradictions; description complements 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?

Two sentences, front-loaded with purpose and metrics. No superfluous words. Every sentence earns its place.

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 tool has one optional parameter, no output schema, but the description explains what the output contains (carbon intensity metrics, marginal CO2). Given low complexity, description is complete enough for an agent to understand and invoke 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% with one optional parameter 'limit' described in the schema. The description does not add parameter semantics beyond schema, so baseline of 3 is appropriate. Use case context is provided but not parameter-level detail.

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 clearly states the tool provides CAISO real-time grid carbon intensity with specific metrics (metric tons CO2 per 5-minute interval, marginal CO2 in lbs/MWh) and example use cases. It differentiates from siblings like caiso_demand, caiso_fuel_mix, and caiso_renewables by focusing on carbon intensity.

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 lists use cases ('what is California grid carbon intensity right now', climate-aware load shifting, hourly emissions reporting), implicitly guiding when to use this tool. It lacks explicit exclusion of when not to use or alternative tools, but the sibling names provide context.

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