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

Annotations already declare the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description still adds real behavioral context: the exact fields returned and the null-when-absent behavior, which the annotations do not convey.

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?

Front-loads the resource and scope, then the return fields, then the key/null note in three tight clauses. No filler, though the entity-type enumeration is somewhat long for the value it adds.

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?

No output schema exists, but the description compensates by naming the returned fields (kind, KNF number, status, dates, services) and the null case. An agent has enough to call it correctly; only sibling-selection guidance is missing.

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 100%, so all three parameters (krs, nip, name) are already documented in the schema. The description only adds that the record is 'keyed by NIP', a marginal hint about primary-key preference that doesn't add syntax or fallback guidance.

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 resource (KNF register / Polish Financial Supervision Authority), the covered entity types (banks, payment/e-money institutions, insurers, agents), and what is returned. This scoping lets an agent distinguish it from the many sibling get_company_* registry lookups without opening the schema.

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?

Provides useful lookup context ('Keyed by NIP; null when the company has no KNF entry'), implying usage for companies that may hold KNF licences. However, it never states when to prefer this over sibling registries (e.g. get_company_sanctions or get_company_stock_market) or any prerequisites, leaving selection to inference.

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