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

Annotations already establish readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds genuinely non-derivable context: the result is null when unlisted and the payload duplicates get_company's sanctions field, both of which affect how an agent interprets an empty response.

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?

Four short sentences, front-loaded with the resource identity, then return shape, then matching, then the de-duplication note. No filler and every sentence carries operational information.

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, the description correctly carries the burden of describing the return ('measures and legal grounds', or null). It is nearly complete for a three-key lookup, missing only multi-match behavior and the REGON reference that the schema does not support.

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 coverage is 100%, so the three keys are documented there, giving a baseline of 3. The description adds the fact that matching works by KRS, NIP or REGON, but REGON is not a parameter in the schema, and with 0 required params it never says which key takes precedence on a mismatch.

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 and resource ('Official MSWiA sanctions listing for one company') and immediately distinguishes it from the sibling set by noting the same payload is also embedded in get_company. An agent can tell this apart from get_company, get_company_debt_registry, etc., without opening any 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?

The line 'The same payload is included on get_company as sanctions' gives the agent a real basis for choosing between the two tools (skip this call if you already fetch get_company). It stops short of an explicit 'use this when / not when' rule, and gives no guidance on which of the three lookup keys to prefer.

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