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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds genuinely new behavioral context the annotations do not: the half-hourly cadence, newest-first ordering, and the pricing model (free within the daily allowance, then $0.002 USDC per call via x402).

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 with no filler: the resource/cadence/ordering come first, and the pricing caveat follows. Every clause carries information an agent can act on.

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?

An output schema exists, so return-value structure need not be restated. The description covers the domain, cadence, ordering, and cost model; only an explicit contrast with interconnector-list 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 parameter baseline is 4. No syntax or filtering semantics are needed, and nothing in the description attempts to invent them.

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 a specific verb+resource ('flows on each interconnector') with cadence (half-hourly), coverage (France, Norway, Netherlands, …), and ordering (newest first). Clear to an agent, though it never explicitly differentiates itself from the sibling gb-electricity__interconnector-list.

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?

Usage is implied by 'latest half-hourly flows' and 'newest first', so the agent can infer when to reach for it. However, there is no explicit when-to-use guidance nor a pointer to interconnector-list for the static catalogue, leaving selection to inference.

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