os_features_query

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is known. The description adds spatial-constraint context but no operational behavior beyond that: it doesn't mention paging, delivery modes, thin mode defaults, bbox guardrails, or payload-size implications. No contradiction with annotations.

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?

One compact sentence front-loads the core action, resource, and spatial constraint, then lists optional capabilities without repetition or filler. It earns its length.

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 20-parameter tool with an output schema, the description is workable but terse. It omits that a bbox or polygon is effectively required according to the schema compatibility note, and it doesn't orient the agent toward pagination, delivery, or resultType choices. The rich schema and annotations prevent this from being a serious failure, but the description alone is not fully sufficient.

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 about 70%, with many parameters already carrying descriptions and enums. The description's phrase 'filter/projection/sort/queryables support' groups several parameters, but it doesn't clarify the less-documented fields (e.g., excludeFields/includeFields, inlineMaxBytes) or the shape of the filter/polygon objects. The schema still carries most of the semantic weight.

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 action ('Query'), a precise resource ('OS NGD features'), and a scoping mechanism ('by collection' with 'bbox or polygon constraints'). This makes the tool's role obvious alongside sibling tools such as os_features_collections and the os_places/os_names lookup tools, without needing to open the 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?

The description gives clear usage context: query feature data within a collection using spatial constraints, optionally with filters, projections, sorting, or queryables. It doesn't name an alternative or give explicit when-not-to-use guidance, but the context is unambiguous enough for a read-only feature query.

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