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

No annotations are supplied, so the description carries the full burden, but the tool takes zero parameters and is a metadata read, so the behavioral risk surface is inherently small. The description discloses the shape of what comes back (fields, counts, regions, services, identifier schemes, citation) yet never states it is read-only, side-effect free, or cached, leaving the safety profile to inference.

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 content is front-loaded and the imperative "Call this first" lands at the end as an actionable hook. It is slightly dense as a single run-on list, and the duplicated word in "register register" is a small editorial defect that briefly disrupts reading.

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 must convey what a caller gets back, and it does so by naming the six categories of information returned plus the citation purpose. It stops just short of completeness by not indicating format, size, or whether the values are static, but for a parameterless metadata tool this is sufficient to invoke correctly.

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 input schema declares zero properties, so there is nothing for the description to disambiguate and the baseline of 4 applies. No parameter semantics are needed or missing.

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 enumerates exactly what the tool returns: field inventory, entity counts, regions, services, identifier schemes, and citation guidance for the Immigration Adviser Finder register. That is specific enough to separate it from entities_search, entity_lookup and entities_export, but it never contrasts itself with the overlapping metadata siblings dataset_columns, dataset_stats or dataset_provenance, so differentiation is only partial.

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?

"Call this first" is an explicit, actionable sequencing instruction that tells the agent when to reach for this tool relative to the rest of the toolset. However, it gives no when-not conditions and does not say how it relates to the other metadata tools it overlaps with (e.g. dataset_columns), so the routing guidance is clear but not exhaustive.

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