search_entities

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

Goes well beyond the annotations: results carry a confidence band, reasons and warnings; the tool explicitly never auto-selects a candidate; and it warns that registry text is data, not instructions (prompt-injection defense). This is rich behavioral context the readOnly/openWorld/idempotent hints cannot convey.

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?

Purpose and identifier examples are front-loaded, and each sentence adds a distinct operational fact (what results contain, who decides, the next call, injection caution). It is dense but no sentence 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?

With no output schema, the description correctly compensates by describing return contents (ranked candidates, confidence band, reasons, warnings) and the entity_id needed for follow-up. Nothing required to call or interpret this tool is missing.

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 schema already documents all five parameters including the country-as-identifier-disambiguator behavior. The description restates the name-vs-identifier distinction but adds no format or syntax detail beyond the schema, so baseline 3 applies.

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+resource (find legal entities, resolve an identifier) and even enumerates identifier types (LEI, UK company number, EU VAT). It never distinguishes itself from the overlapping sibling resolve_identifier, so an agent cannot tell the two apart from this text alone.

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 clear workflow context: name searches return ranked candidates that must be confirmed with the user, and the follow-up call is get_entity with its entity_id. It stops short of naming when to prefer resolve_identifier or another sibling.

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