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

The annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds useful context beyond the annotations: the search is UK Companies House-specific, uses free-text input, and returns a registration number. It does not contradict 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 a single, focused sentence that states the search scope, input type, and output. Every word contributes meaning, and it is front-loaded with the primary behavior.

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?

The tool has no output schema and zero schema documentation for its parameters. While the description covers the main purpose and output, it omits limit semantics, result shape, and pagination or return-list behavior. This is adequate for a simple read-only search tool but not fully complete.

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 0%, so the description must compensate. It implies q is the free-text company name, but the 'limit' parameter is entirely undocumented in both the schema and description. This leaves a meaningful gap in parameter understanding.

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 identifies the tool: it performs a free-text UK Companies House company-name search and returns a registration number. This distinguishes it from siblings like search_entities or lookup_by_identifier by specifying the jurisdiction, scope, and output.

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 implies when to use the tool—when you need to search for a UK company by name—but it does not explicitly state when not to use it or mention alternatives. With many sibling tools available, there is no direct comparison or exclusion guidance.

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