haversine_distance

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It mentions 'Compute' and 'exact great-circle', which implies a pure calculation, but it does not explicitly state that it has no side effects, requires no permissions, or what happens with invalid inputs. It also does not note any limitations (e.g., Earth's oblateness). The description adds algorithmic context but leaves safety and side-effect details implicit.

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 is a single, front-loaded sentence that conveys the core action and scope without any filler. It is appropriately concise for a tool of this simplicity, and every word contributes to understanding.

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 should specify the return value. It says 'in km/miles' but does not clarify whether it returns a single number in one of the units, both units, or allows the caller to choose. It also does not mention expected input units (e.g., decimal degrees) or any edge cases like anti-meridian crossings. For a four-parameter tool, this is incomplete.

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 description coverage is 0%, so the description must explain parameters. It says 'two lat/long coordinates' but does not map them to the four parameters (lat1, lon1, lat2, lon2), nor specify units (degrees vs radians) or the order of the coordinate pairs. The parameter names are self-explanatory, but the description adds no additional semantic value beyond what the property names already convey.

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 clearly states the action ('Compute'), the object (great-circle distance), and the context (two lat/long coordinates). It distinguishes itself from sibling tools like levenshtein_distance or calculate, which serve different purposes. The verb and resource are specific and unambiguous.

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?

There is no guidance on when to use this tool versus alternatives, no exclusions, and no prerequisites. The description does not state 'Use this when you need distance between two geographic points', leaving the agent to infer its usage from the name and description. This is a minimal-viable hint but lacks explicit direction.

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