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

Annotations already declare the tool as read-only, open-world, idempotent, and non-destructive. The description adds valuable behavior: 'Sources are tried in cascade; quality_score increases with each source that succeeds.' It also discloses coverage nuances and optional keys, which are not in the annotations.

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 dense but appropriately sized for a multi-source tool. It front-loads purpose and return value, then coverage, then usage. No sentence is wasted, though it is a single paragraph that could benefit from slight restructuring (e.g., bullets for coverage).

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?

Despite having an output schema not shown, the description lists the returned fields (legal status, registration number, directors, etc.) and the quality score. It also covers async behavior, country inference, and optional keys, making it complete for an agent to invoke and interpret results.

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%, so the baseline is 3. The description adds minor context (e.g., country inference, cascade behavior) but does not fundamentally extend parameter understanding beyond what the schema already provides.

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 opens with a specific verb+resource: 'Resolve legal information about a company from its national corporate registry.' It clearly distinguishes the tool from siblings like kyc_screener and sanctions_screener_multi by focusing on corporate registry data and explicitly stating the use cases.

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?

Provides explicit context: 'When to use: due-diligence, KYC screening, supplier verification, M&A research, or any workflow needing verified company identity and legal status.' It does not mention exclusions or alternatives, but the coverage and key requirements are clear enough for an agent to decide when to invoke it.

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