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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely non-structured context: the data is served under Pipeworx's own GIE key so no auth setup is needed, and callers may override with their own free key via _apiKey. It does not mention rate limits or latency for large day ranges.

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?

Three dense sentences, front-loaded with what the tool returns before the scoping and auth notes. No filler, though the parenthetical unit list is slightly heavy inside the opening sentence.

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 an 8-parameter, no-output-schema read tool, the description covers data source, units, granularity options, date defaulting and auth handling — enough to call it correctly. The main residual gap is the response shape/row structure, which is not disambiguated anywhere since there is no output schema.

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 description coverage is 100%, so every parameter is already documented, and the description largely restates that (date omission, country/company/facility hierarchy, units). It adds the useful framing of the aggregation grain ordering but no format or constraint detail beyond the schema. Baseline 3 is appropriate.

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 ('European LNG terminal levels from GIE ALSI+') and enumerates the exact measures returned: tank inventory in 1000 m3 LNG and GWh, daily send-out, and declared max capacity. It also names the four aggregation grains (EU, country, operator, terminal), making it clearly distinguishable from the sibling gie_gas_storage (storage vs LNG terminals).

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?

Gives a clear operating rule ('omit dates for the latest gas day') and encodes dependency guidance implicitly through the grain hierarchy, with concrete country-code examples (ES, FR). It does not explicitly contrast itself against gie_gas_storage or gie_storage_facilities, which would be the natural alternatives, so it stops short of the top score.

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