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

No annotations are provided, so the description carries the full burden. It discloses the matching mode (exact) and the return shape (whole record with its page), but says nothing about authentication needs, rate limits, or what happens when no match is found — meaningful gaps 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 tight sentences that front-load the resource and lookup keys, then the matching semantics and return. No filler, though the parenthetical example is slightly compressed.

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?

For a 3-parameter, no-annotation, no-output-schema tool, the description covers the lookup keys, matching behavior, and return value. The remaining gap is whether `slug` and `scheme`+`value` are mutually exclusive and what an empty result looks like.

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 only 33% (only `scheme` is documented), so the description must compensate. It does by explaining that `scheme` + `value` form a composite register identifier with an example (lei), and that `slug` is an alternative key — context the bare schema does not convey, especially given zero required parameters.

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 specific verb+resource: retrieving the single register entry for a firm, either by register identifier or by page slug. It distinguishes itself from sibling search-style tools by explicitly declaring 'Exact match', though it does not name the alternatives (entities_search, entities_in) directly.

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 implies when to use it (exact single-record retrieval) and offers two lookup paths, but never says when NOT to use it or points to entities_search for fuzzy/partial matching. Usage is inferable rather than explicit.

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