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

Annotations already declare this a read-only, non-destructive, closed-world lookup, so the safety profile is covered. The description adds genuinely useful context the annotations do not: prices are indicative 2026 figures and are confirmed on the booking call with a vetted local operator, signaling the data is not authoritative.

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?

Three tight sentences: scope, the required-input rule, and the accuracy caveat, in that order. Nothing is repeated and every sentence carries information the agent needs.

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?

With no output schema, the description usefully summarizes the return shape (low/median/high GBP per skip size) and the mutual-exclusion input rule, and annotations cover the safety profile. It does not say what happens for an uncovered area, which is a minor gap for a read-only lookup.

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 100%, which sets a baseline of 3, but the description contributes a constraint the schema does not encode: exactly one of town_slug or postcode_area must be supplied (the schema has no oneOf and zero required parameters). It also clarifies that values represent a town or a postcode area.

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 names a specific resource (skip hire price ranges: low/median/high in GBP per skip size) and the two input scopes (town or postcode area), which is enough to distinguish it from check_coverage, get_permit_info and recommend_skip_size. It is clear but stops short of explicitly naming how it differs from those siblings.

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?

'Provide exactly one of town_slug or postcode_area' is a real usage constraint, and the schema points to check_coverage for finding a town slug. However, there is no explicit statement of when to reach for this tool versus the sibling price/coverage/size tools, so the routing guidance is only implied.

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