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

With no annotations, the description must disclose behavioral details. It states a read-only list operation, but fails to mention that active_only defaults to true and cluster being null likely means all clusters, both of which materially affect results.

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?

Single sentence, clear verb-first structure, no filler. It is concise, though slightly under-specified for the two parameters.

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 output schema covers return structure, but the description omits parameter semantics and default filtering behavior. For an operation with two optional parameters and no annotations, this is insufficient for confident invocation.

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% and the description does not explain either parameter. cluster is ambiguous and active_only's effect is left to inference, so the description adds no meaning beyond parameter names and types.

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?

Description uses a specific verb ('List') and resource ('registered ENTSO-E bidding zones'), making the tool's function unmistakable. It also distinguishes itself from sibling list tools like list_derivations and list_psr_types by naming the exact resource type.

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 action is implied: use this when you need the set of bidding zones. However, there is no explicit guidance about when not to use it or how it compares to sibling tools such as compare_zones or data_coverage.

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