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

With no annotations, the description carries the full burden, and it does disclose what the payload contains (daily series of fill level, TWh, flows, and multi-horizon comparisons), which is genuinely useful given there is no output schema. It says nothing about authentication, update frequency, or read-only behavior, so the disclosure is partial.

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 sentence, front-loaded with the resource and source before the metric list. Every clause carries information; the only cost is that the long comma list makes it slightly hard to scan.

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 2-parameter read tool with no output schema and no annotations, the description covers return content well but leaves key gaps: parameter semantics, the default EU-wide scope, and any indication of data freshness or rate limits. Adequate but not sufficient on its own.

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 0%, so the description must explain both `days` and `country`. 'EU and every EU country with storage' weakly implies the country parameter defaults to EU-wide, and 'daily series' hints at the time dimension, but the meaning, defaults, and units of `days` are never addressed.

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 names a specific resource (EU gas storage), its source (GIE AGSI+), and enumerates the exact metrics returned: fill level, stored TWh, injection/withdrawal, 7-day change, year-on-year and five-year-average comparisons. It is clearly a data-retrieval tool, though it never explicitly contrasts itself with siblings like get_europe_energy_prices or get_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?

There is no stated when-to-use guidance, no prerequisites, and no named alternative. The scope phrase 'EU and every EU country with storage' hints at coverage but does not tell an agent when this tool beats the energy-prices or LNG siblings. Usage must be entirely inferred.

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