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

With no annotations, the description carries the full behavioral burden. It does disclose that results are computed over the 'current snapshot' (useful temporal scope), but says nothing about permissions, rate limits, or the structure of what is returned. This is thin for a no-annotation tool.

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?

Two compact sentences with the operational content front-loaded; the bracketed license/attribution block is boilerplate but short. Nothing substantial is wasted.

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 and no annotations, the description should more fully describe what the aggregate response contains. It names the grouping dimensions but leaves the return shape and access requirements unclear, so it is only adequate.

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?

The tool takes zero parameters, and the description lists the aggregation dimensions (type, status, Bundesland), which gives useful semantic context even though there are no inputs to document.

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 clear verb (aggregate counts) and resource (German MaStR energy units), plus the grouping dimensions (type, status, Bundesland). This clearly distinguishes it from siblings like mastr_search_units and mastr_get_unit, though it never names those alternatives explicitly.

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?

Usage is only implied: an agent can infer this is for aggregate/summary views rather than individual unit lookups. There is no explicit when-to-use guidance, no exclusions, and no naming of sibling tools for contrast.

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