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

With no annotations provided, the description carries the full behavioral disclosure burden. It clearly discloses that start is inclusive, end is exclusive, times default to UTC, the server converts local timezone inputs at the boundary, and the response's period block lets the user verify the resolved window. It does not explicitly disclose pagination or row-cap behavior for this endpoint itself, and the aggregation parameter behavior is not described.

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?

The description is dense but well-organized, with each paragraph covering a distinct concern: core purpose, date/time semantics, and alternative routing. Every sentence earns its place, and the most important boundary caveat is front-loaded with a concrete example.

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?

The tool has an output schema, so return-value detail need not be spelled out; the description covers the main invocation pitfalls such as EXCLUSIVE end dates, UTC default, and timezone conversion. The only material gap is the undocumented aggregation parameter, which prevents the definition from being fully complete for all call shapes.

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 0%, so the description must compensate. It adds strong semantics for start/end and tz, including a concrete April example and the 'local' vs IANA timezone option. However, the aggregation parameter is never explained, which is a significant gap since it has a default of 'raw' but no enum or schema description.

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 first line states the tool returns 'Day-ahead clearing price (EUR/MWh) for a bidding zone,' which is a specific, unambiguous resource. It also distinguishes itself from get_derivation by naming the alternative for generation-weighted metrics, so an agent can immediately tell this endpoint apart from siblings.

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 description gives explicit when-to-use guidance: if computing generation-weighted metrics, use get_derivation('slug="capture_price"') instead, with reasoning about server-side computation and no row cap. It also explains timezone interpretation and the inclusive/exclusive date boundary, preventing common misuse.

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