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

Goes well beyond the annotations by disclosing the pricing model (charged per property answered, sum of single calls, not_covered rows free) and the partial-failure contract (per-item outcomes in input order). It does not state behavior when more than 100 UPRNs are supplied or whether batches partially charge on upstream failure, which keeps it from a 5 given the annotations already cover safety.

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?

Four compact clauses, front-loaded with what the tool is, followed by outcome semantics, cost, and the UPRN resolution path. No filler, and the cost/monetization detail sits where an agent will see it before deciding to call.

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?

Output schema exists, yet the description still summarizes the per-item outcome enum and ordering guarantee, which is the piece an agent needs to reason about partial failures. Combined with pricing, geography, and the UPRN resolution workflow, nothing material is missing for correct invocation.

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?

With a single parameter and 0% schema description coverage, the description carries the burden and does so: it explains that the key is a UPRN (integer identifier), not an address string, and that the array is capped at 100 items. It could still name the parameter explicitly or describe item-level validation errors, but the essential semantics are supplied.

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 (batch-fetch), resource (planning histories), and scope (up to 100 properties in one call). It explicitly frames itself as the batch form of the sibling `property_planning_history`, so an agent can distinguish the two without inspecting schemas.

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?

Gives explicit prerequisites and the alternative path: 'Keyed on a UPRN, not an address: call `address_autocomplete` (free) to narrow, then `address_resolve` to get one.' It also states the 'UK only' applicability constraint, so when-not-to-use is implied by geography.

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