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

Annotations already declare the safe-read profile (readOnly, idempotent, non-destructive, openWorld), so the description's main added value is the cost model: free within the daily allowance, then $0.001 USDC per call via x402. That is genuine behavioral context an agent cannot get from annotations or schema, though it does not cover cadence of publication or revision behavior.

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 tightly packed sentences that front-load what the data is before pricing. No filler or redundant restatement of the title.

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, return values need no explanation, and with zero parameters there is nothing to document. Scope, cadence, window, and cost are all covered; only sibling-routing guidance is missing.

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 tool takes zero parameters, so the baseline is 4. There is nothing for the description to disambiguate beyond the absence of filters, which is not stated but also not needed.

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?

States the resource (national and transmission demand outturn), the temporal resolution (half-hourly), and the window (~2 days), which distinguishes it from siblings like demand-daily, demand-peak, and the demand-forecast family. The word 'Initial' is slightly ambiguous (initial estimate vs outturn revision) but the resource is identifiable.

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 'last ~2 days' hint implies recency, but there is no explicit guidance on when to pick this over demand-daily, demand-peak, or demand-forecast. An agent must infer the choice from the window alone.

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