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

Annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds the useful workflow trait that results are ids intended for a follow-up fetch call, which is not derivable from the annotations — though it does not discuss result counts, relevance ranking, or empty-result behavior.

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 sentences, both load-bearing: the first gives scope and return contract, the second handles sibling routing. Front-loaded with no filler.

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 single-parameter lookup tool with an output schema and full annotation coverage, the description supplies everything an agent needs: what is searchable, what comes back, and which sibling to use instead when structured results are required.

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 0%, so the description must carry the query semantics; it does by enumerating what the query string may contain (company name, licence number, company number). Constraints like the 100-character maximum and the single-required-parameter shape are left to 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?

States a specific verb (search), the resource (HaulierScope operators and guides), the accepted identifier types (company name, licence number, company number), and the return contract (ids to pass to fetch). It also explicitly distinguishes itself from the sibling search_operators, which is the operator-results tool.

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 routes the agent: use this tool to obtain ids for fetch, and prefer search_operators when structured operator results are wanted. Both the condition for using this tool and the alternative for the adjacent case are named.

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