search_companies

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

No annotations are provided, so the description carries the full burden. It does useful work by naming the returned fields (number, status, address snippet, incorporation date), which tells the agent this is a non-destructive read and what to expect. However, it says nothing about result ordering/'best match' semantics, rate limits, or pagination beyond the page size.

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?

Front-loaded with the core action and return shape, then a compact Args block. Every sentence is useful; the Args block is minimally redundant with the schema but serves as a fallback given zero schema descriptions.

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 two-parameter search with a sibling for follow-up lookup, the description covers purpose, return fields, and the hand-off to get_company. Since an output schema exists, return values need not be detailed, and the remaining gaps (ordering, no-match behavior) are minor.

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, and it does: 'query' is explained with concrete examples ('Driver Plumbing', 'TESCO') and 'items_per_page' gets a range and default (1-100, default 10) that the schema itself omits. Only the integer type/format nuance is left implicit.

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 and resource ('Search the UK company register by name') and lists the returned fields, so the agent knows exactly what comes back. It also distinguishes itself from the sibling get_company by explaining that this is the name-lookup entry point.

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 forward: 'use the company_number from the best match with get_company.' That is a clear when-to-use chain, but there is no exclusion guidance (e.g., what to do if no match is found, or when to skip straight to a number lookup).

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