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

With no annotations, the description carries the full transparency burden and partially meets it by stating 'Pure computation', which signals no side effects or external state changes. It also discloses the GB-only scope for BNG and the mgrs_precision range/default, plus the exact JSON response shape. It does not mention behavior on invalid lat/lon values, but the pure-computation framing covers the main risk of side effects.

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?

The description front-loads the core purpose and then adds parameter and return details in a logical order. The list of output formats is long but necessary, though the 'Returns JSON' block is partially redundant given an output schema exists.

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 compute-only formatting tool with three parameters and no annotations, the description covers the essential invocation context: input point, output formats, precision, GB-only caveat, and response fields. It does not explicitly address coordinate range validation or behavior on invalid input, but the output schema and pure-computation nature lower that burden.

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?

Input schema coverage is 0%, so the description must compensate. It clearly explains mgrs_precision (1-5 digit pairs, default 5), but lat and lon are only inferred from 'WGS84 point' and their parameter names; input format, units, and bounds are not explicitly stated.

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 opening phrase 'Express one WGS84 point in every common notation at once' names a specific verb, resource, and scope, and enumerates output formats in enough detail to distinguish it from single-format siblings like convert_coordinates or parse_coordinate. The 'at once' emphasis clearly differentiates it from one-off conversion tools.

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 implies its usage niche through 'every common notation at once' and gives a scope caveat with 'inside GB only' for BNG, but it never explicitly names alternatives or states when to prefer this tool over simpler coordinate conversion tools. There is no direct when-to-use or when-not-to-use guidance.

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