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

Annotations declare readOnlyHint=true and destructiveHint=false, so the agent knows it's a safe read operation. The description adds important behavioral context: real-time telemetry, single-ISO scope ('for one ISO'), and the data source via EIA. It also implies potential rate/size constraints by warning against heavy analyses. Minor deduction for not explicitly stating response size or rate limits, but this is well-covered for the read-only annotation.

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 paragraph front-loads the core purpose before routing to alternatives. Every clause earns its place; no filler words.

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?

For a read-only, idempotent tool with full schema coverage and no nested objects, this description covers purpose, usage, provenance, and scope completely. The explicit exclusions preempt common agent mis-selections and cover the highest-risk failure modes.

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 covers 100% of parameters, so the baseline is 3. The description adds value by giving a concrete example ('Pass iso=PJM'), reminding that iso is required despite schema listing it as optional, and naming the valid ISOs. This example meaningfully reduces agent confusion about the parameter format.

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 real-time electricity grid data for 7 specific US ISOs, listing each abbreviation. It names the source (EIA hourly RTO) and specific data types (fuel mix, demand, 24h demand curve). This distinguishes it from many siblings, and explicitly names get_grid_intelligence and get_energy_prices as alternatives for other use cases.

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?

Provides explicit when-to-use and when-not-to-use guidance. It states the tool is for real-time telemetry and explicitly directs away from power-availability, time-to-power, interconnection-queue, and retail/gas pricing analyses to get_grid_intelligence and get_energy_prices. It also gives global alternatives (get_grid_scoreboard) for non-US grids. This is a model of clear routing.

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