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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds value by noting that the tool handles trade-name variants via normalization and includes mandatory NTA attribution in the output, which are not covered by 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 three sentences, each earning its place: first sentence states the core purpose and return values, second sentence notes variant handling, third sentence provides usage guidance and sibling reference. No fluff.

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 read-only tool with one parameter, the description is comprehensive. It explains what is returned, variant handling, source, and alternative tool. No output schema exists, but the description adequately covers return values.

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?

The single parameter 'name' is fully described in the input schema (100% coverage). The description enhances this by providing an explicit example and noting that variants like ㈱ are accepted, adding practical guidance beyond the 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?

The description clearly states the tool searches the Japanese corporate-number registry by company name and returns matching companies with corporate number, name, address, and NTA attribution. It also distinguishes from the sibling tool corporation_lookup by specifying the direction of the 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?

Explicitly states when to use the tool (when an AI agent has a company name and needs to resolve its corporate number/canonical record) and when not to use it (to go the other way, use corporation_lookup). This provides clear context for tool selection.

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