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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine value by disclosing the returned data set (board & representation, proxies, liquidation/bankruptcy flags), which is important given there is no output schema. It does not address failure behavior for unknown KRS numbers or data freshness beyond the word 'current'.

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?

A single dense sentence with zero filler, front-loaded on the resource type, followed by the returned fields. Nothing is redundant and nothing needs trimming.

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 one-parameter, read-only registry lookup with no output schema, the description compensates well by enumerating the returned fields and heading off the missing-return-schema gap. The remaining shortfall is routing context relative to the other company-lookup siblings, which an agent would still have to guess.

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?

There is one parameter ('krs') with 100% schema description coverage including an example format (0000028860). The description adds no parameter detail, but at this coverage level the schema fully carries the burden and the single required identifier is unambiguous.

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 names a specific resource (current KRS extract) and enumerates the exact data it returns (legal form, address, share capital, board, PKD codes, flags), so an agent immediately knows what comes back. It stops short of a 5 because it never distinguishes itself from siblings like find_company or contractor_due_diligence, leaving the agent to infer that this is the KRS-number lookup path.

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?

There is no explicit when-to-use statement and no named alternative. Usage is only implied: an agent must infer from the name and the required 'krs' parameter that this is the registry-lookup route, while find_company presumably handles name-based discovery. A sentence such as 'use when you already have the KRS number' would have lifted this.

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