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

With no annotations, the description carries the full burden and does well: it discloses cost (FREE), data freshness (today's Home Office register), return contents (rating A/B and routes) and result truncation (top 3 matches). It omits what happens on zero matches or whether matching is exact or fuzzy, keeping it short of a 5.

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 tight sentences with the cost signal and the core question front-loaded; every clause carries information. The em-dash tail is slightly compressed but not wasteful.

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 one-parameter tool with no output schema it covers the essentials: what it returns, how many results, and how fresh the data is. The only real gap is no-match and matching-semantics behavior, which would matter to an agent deciding whether to retry.

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 compensate for the single 'organisation' parameter. It implies the value is an organisation name and that matching is loose ('top 3 matches'), but adds no format guidance such as trading name vs registered name.

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 question the tool answers (is this organisation a licensed UK visa sponsor) plus the output shape (rating A/B, routes). It does not explicitly distinguish itself from the sibling sponsor_search, so an agent must infer the difference.

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 leading 'FREE' signals a cost preference and 'top 3 matches' implies fuzzy lookup, giving implied usage context. However, it never says when to use this versus sponsor_search or b_rated, and offers no exclusions.

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