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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior; the description adds the cost model ('Flat 5 points per successful run') and enumerates returned attributes. It does not cover auth or failure modes, but with annotations carrying the safety profile this is useful added context.

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?

Two tight sentences, front-loaded with purpose and lookup mode, followed by return fields and pricing. Every clause carries information relevant to invoking or assessing the tool.

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 simple one-parameter lookup with no output schema, the description supplies the returned fields, source registry, and cost. Annotations and schema cover safety and parameter details, so an agent has enough 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 the single parameter is fully described there. The description repeats the same registration-number-or-URL semantics without adding format, validation, or failure behavior, so it meets the baseline for a fully documented schema.

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 (Get) and resource (one company) from the Estonia e-Business Register, including lookup keys and returned fields. The 'one company' scope distinguishes it from run_ee_companies_search without needing to open 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?

Specifies the input condition (registration number or registry URL), which tells the agent when this lookup is appropriate. It does not name the search alternative or state when to avoid this tool, so it stops short of full routing guidance.

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