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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds meaningful context beyond that: the per-signal payload shape (value with unit, percentile, confidence plus the engine's reason, source, observation period) and the depth of deprivation data with deciles, rank and score.

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-loads the verb and resource, then uses the remaining space for payload detail and sibling routing. The long enumerations of categories and returned fields are dense but each clause carries information; no filler sentences.

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 is responsible for conveying what comes back, and it does so in reasonable detail (value/unit, percentile, confidence, source, period, deprivation deciles). It stops short of describing volume, pagination or handling of sparse coverage, which an agent calling for 'every signal' might care about.

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%, so both the area formats and the sort enum are fully documented in the schema itself. The description adds nothing about parameter syntax or defaults beyond restating the geographic scope, so the baseline 3 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?

States a specific verb and resource ('Returns every signal OneGoodArea holds for one place') plus the geographic scope (England, Wales or Scotland) and the full category coverage. It also explicitly names the sibling it is not (get_signals_by_category), so an agent can choose between them without opening either schema.

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?

Provides a clear selection rule: use this for all data behind every score, and get_signals_by_category when only one category is needed. It lacks explicit exclusions (e.g. outside Great Britain, or when a targeted score lookup is preferable), but the named alternative is enough to route most calls correctly.

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