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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds significant behavioral detail: output exposes only birth_year (never full birth date), and same-name person_ids are kept separate with a distinguisher. This goes beyond the annotations and informs the agent about privacy-preserving behavior and disambiguation, which is genuinely useful.

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?

The description is three sentences, each earning its place: core purpose, free anonymous nature, and input/output behavioral specifics. It is front-loaded with the main verb and resource, and contains no redundant filler or repeated structured data.

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 covers return behavior well by stating the output's constraints (birth_year only, never full birth date, same-name person_ids separated). It implies the output is companies, given the lookup purpose. Slight gap: it doesn't explicitly enumerate other output fields, but it is adequate for a simple lookup tool.

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%, with both 'name' and 'birth_year' already described. The description adds minimal extra parameter semantics—it repeats that input accepts a public name and optional birth year, but does not clarify anything beyond the schema. Therefore the baseline of 3 is appropriate.

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 states a specific verb ('Look up') and resource ('Czech VR companies'), and further specifies the join path ('exact registry person_id -> roles -> companies joins'). This clearly differentiates it from sibling detection/risk tools, which focus on analysis rather than basic lookup.

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 description provides clear usage context: it's a free anonymous lookup for exact matches in the Czech VR registry, requiring a public name and optionally a birth year. It implies its use when you need company associations by person, and the sibling set (detection tools) is obviously different. However, it does not explicitly state exclusions or alternatives, so it stops short of a 5.

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