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

Annotations already declare readOnlyHint and destructiveHint=false, so "reads public registries and does not change them" largely restates them. However, it adds genuinely new operational context beyond the annotations: no API key required and a daily per-IP rate limit, which materially affects agent planning.

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?

Three tight sentences: what it produces, how to invoke it, then the safety/auth/limit context. The distinctive value (normalized merged profile) is front-loaded and nothing is padded.

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?

An output schema exists, so return values need not be explained. Still, the description omits how conflicts between MF and KRS data are resolved, error behavior when the identifier is absent or invalid, and it silently diverges from the schema's zero required parameters by demanding one identifier.

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 all three identifiers are undocumented in the schema, so the description carries the load. It contributes the at-least-one-identifier rule ("provide one of") that the empty required array does not convey, but gives no format details (NIP/REGON/KRS digit lengths, checksum expectations despite the nip_checksum sibling).

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 concrete action (combine/merge MF VAT white list and KRS into one normalized profile) plus the resource (a Polish company). It implicitly distinguishes itself from the single-source siblings (check_vat_whitelist, get_krs_extract, vies_check) by emphasizing the merged, normalized result, though it never names them.

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?

"Provide one of nip, regon or krs" is a usable invocation constraint, but there is no guidance on when to call this merged lookup versus the narrower per-registry siblings, and no mention of what happens for unregistered or partially registered entities.

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