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

Annotations already declare readOnly/idempotent/openWorld, and the description adds value beyond them: it names the upstream source (RIK e-Business Register open data), enumerates the returned facets (identity, status including liquidation/bankruptcy, address, EMTAK/NACE), and discloses the exact-match failure mode for renamed companies.

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-loaded with the core purpose and no filler sentences; every clause carries information. The RIK parenthetical and long compound sentences make it denser than it needs to be, but nothing is wasted.

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, so the description must describe return values, which it does (identity, status, address, activity areas). Combined with the exact-match caveat and sibling routing, an agent has everything needed to call it correctly.

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% and both parameters are documented with examples, so the schema does the heavy lifting. The description adds real meaning on top, though: it clarifies that the name must be the CURRENT registered name and that registry code is the fallback when a company was renamed.

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: retrieves one Estonian company or registered entity by registry code or exact name. It names the sibling it is not (ee_company_search for partial matches), so an agent can route without opening either 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?

Gives explicit trigger examples ("what is the status of registry code 12417834"), a named alternative for partial names, and a stated when-not: former names will not match by name, so use registry code instead. That is unusually complete routing guidance.

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