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

Annotations already establish readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuinely new behavioral context: it reports a point-in-time state ('free right now') plus a data-freshness signal ('when they last set their availability'), which is meaningful given there is no output schema.

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?

A single tight sentence that front-loads the core action ('Check whether one specific named business is free right now') before the secondary return detail and the usage rule. No filler or redundancy.

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 2-parameter read tool with full schema coverage and annotations handling the safety profile, the description is nearly complete and even hints at return content. It omits only edge behavior such as what happens when the name matches nothing or is ambiguous across branches.

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% and both parameters are already well documented in the schema, including the 50-mile widening behavior for postcode. The description adds nothing about parameter format or matching semantics (e.g., partial-name matching), so the baseline 3 for schema-covered params 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?

The description gives a specific verb and resource (check availability for a single named business) and pins the scope with 'one specific named business.' That singular framing implicitly contrasts with the plural sibling find_available_providers, but the sibling is never named, so differentiation is inferred rather than stated.

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?

'Use this when someone names a business rather than a trade' is an explicit routing rule that separates this tool from the trade-search path. It gives a clear positive condition but does not name the alternative tool or state any exclusion (e.g., what to do when only a trade is known).

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