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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so safety is covered. The description's added value is the pinned regulatory basis (2025/2621 as corrected by 2026/1740), which matters for a versioned legal dataset, but it says nothing about unpaginated bulk returns or the no-filter default.

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 front-loaded sentence with no filler; the regulation citations are dense but load-bearing for a versioned regulatory dataset.

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 no output schema, the description never indicates what is returned (default emission values per CN/origin/sector, presumably) or how results behave when no filters are supplied, leaving a real gap for a zero-required-parameter lookup tool.

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%, including the ROW fallback and the sector enum, so the schema carries parameter meaning. The description only restates the three filter axes and adds no semantics such as prefix-match behavior or AND/OR combination rules.

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?

Names a specific verb (search) and a specific resource (EC default emission values dataset) plus the three filter dimensions, so an agent can tell what it retrieves. It doesn't explicitly contrast with any sibling, but the resource is distinct enough from cbam_certificate_price, cbam_scope and cbam_status that ambiguity is low.

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 listed filter dimensions imply how the tool is used, but there is no statement about when to prefer it over siblings, whether filters can be combined, or what happens when called with zero required parameters.

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